Root/drivers/gpu/drm/drm_irq.c

1/**
2 * \file drm_irq.c
3 * IRQ support
4 *
5 * \author Rickard E. (Rik) Faith <faith@valinux.com>
6 * \author Gareth Hughes <gareth@valinux.com>
7 */
8
9/*
10 * Created: Fri Mar 19 14:30:16 1999 by faith@valinux.com
11 *
12 * Copyright 1999, 2000 Precision Insight, Inc., Cedar Park, Texas.
13 * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
14 * All Rights Reserved.
15 *
16 * Permission is hereby granted, free of charge, to any person obtaining a
17 * copy of this software and associated documentation files (the "Software"),
18 * to deal in the Software without restriction, including without limitation
19 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
20 * and/or sell copies of the Software, and to permit persons to whom the
21 * Software is furnished to do so, subject to the following conditions:
22 *
23 * The above copyright notice and this permission notice (including the next
24 * paragraph) shall be included in all copies or substantial portions of the
25 * Software.
26 *
27 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
28 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
29 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
30 * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
31 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
32 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
33 * OTHER DEALINGS IN THE SOFTWARE.
34 */
35
36#include "drmP.h"
37#include "drm_trace.h"
38
39#include <linux/interrupt.h> /* For task queue support */
40#include <linux/slab.h>
41
42#include <linux/vgaarb.h>
43#include <linux/export.h>
44
45/* Access macro for slots in vblank timestamp ringbuffer. */
46#define vblanktimestamp(dev, crtc, count) ( \
47    (dev)->_vblank_time[(crtc) * DRM_VBLANKTIME_RBSIZE + \
48    ((count) % DRM_VBLANKTIME_RBSIZE)])
49
50/* Retry timestamp calculation up to 3 times to satisfy
51 * drm_timestamp_precision before giving up.
52 */
53#define DRM_TIMESTAMP_MAXRETRIES 3
54
55/* Threshold in nanoseconds for detection of redundant
56 * vblank irq in drm_handle_vblank(). 1 msec should be ok.
57 */
58#define DRM_REDUNDANT_VBLIRQ_THRESH_NS 1000000
59
60/**
61 * Get interrupt from bus id.
62 *
63 * \param inode device inode.
64 * \param file_priv DRM file private.
65 * \param cmd command.
66 * \param arg user argument, pointing to a drm_irq_busid structure.
67 * \return zero on success or a negative number on failure.
68 *
69 * Finds the PCI device with the specified bus id and gets its IRQ number.
70 * This IOCTL is deprecated, and will now return EINVAL for any busid not equal
71 * to that of the device that this DRM instance attached to.
72 */
73int drm_irq_by_busid(struct drm_device *dev, void *data,
74             struct drm_file *file_priv)
75{
76    struct drm_irq_busid *p = data;
77
78    if (!dev->driver->bus->irq_by_busid)
79        return -EINVAL;
80
81    if (!drm_core_check_feature(dev, DRIVER_HAVE_IRQ))
82        return -EINVAL;
83
84    return dev->driver->bus->irq_by_busid(dev, p);
85}
86
87/*
88 * Clear vblank timestamp buffer for a crtc.
89 */
90static void clear_vblank_timestamps(struct drm_device *dev, int crtc)
91{
92    memset(&dev->_vblank_time[crtc * DRM_VBLANKTIME_RBSIZE], 0,
93        DRM_VBLANKTIME_RBSIZE * sizeof(struct timeval));
94}
95
96/*
97 * Disable vblank irq's on crtc, make sure that last vblank count
98 * of hardware and corresponding consistent software vblank counter
99 * are preserved, even if there are any spurious vblank irq's after
100 * disable.
101 */
102static void vblank_disable_and_save(struct drm_device *dev, int crtc)
103{
104    unsigned long irqflags;
105    u32 vblcount;
106    s64 diff_ns;
107    int vblrc;
108    struct timeval tvblank;
109
110    /* Prevent vblank irq processing while disabling vblank irqs,
111     * so no updates of timestamps or count can happen after we've
112     * disabled. Needed to prevent races in case of delayed irq's.
113     */
114    spin_lock_irqsave(&dev->vblank_time_lock, irqflags);
115
116    dev->driver->disable_vblank(dev, crtc);
117    dev->vblank_enabled[crtc] = 0;
118
119    /* No further vblank irq's will be processed after
120     * this point. Get current hardware vblank count and
121     * vblank timestamp, repeat until they are consistent.
122     *
123     * FIXME: There is still a race condition here and in
124     * drm_update_vblank_count() which can cause off-by-one
125     * reinitialization of software vblank counter. If gpu
126     * vblank counter doesn't increment exactly at the leading
127     * edge of a vblank interval, then we can lose 1 count if
128     * we happen to execute between start of vblank and the
129     * delayed gpu counter increment.
130     */
131    do {
132        dev->last_vblank[crtc] = dev->driver->get_vblank_counter(dev, crtc);
133        vblrc = drm_get_last_vbltimestamp(dev, crtc, &tvblank, 0);
134    } while (dev->last_vblank[crtc] != dev->driver->get_vblank_counter(dev, crtc));
135
136    /* Compute time difference to stored timestamp of last vblank
137     * as updated by last invocation of drm_handle_vblank() in vblank irq.
138     */
139    vblcount = atomic_read(&dev->_vblank_count[crtc]);
140    diff_ns = timeval_to_ns(&tvblank) -
141          timeval_to_ns(&vblanktimestamp(dev, crtc, vblcount));
142
143    /* If there is at least 1 msec difference between the last stored
144     * timestamp and tvblank, then we are currently executing our
145     * disable inside a new vblank interval, the tvblank timestamp
146     * corresponds to this new vblank interval and the irq handler
147     * for this vblank didn't run yet and won't run due to our disable.
148     * Therefore we need to do the job of drm_handle_vblank() and
149     * increment the vblank counter by one to account for this vblank.
150     *
151     * Skip this step if there isn't any high precision timestamp
152     * available. In that case we can't account for this and just
153     * hope for the best.
154     */
155    if ((vblrc > 0) && (abs64(diff_ns) > 1000000)) {
156        atomic_inc(&dev->_vblank_count[crtc]);
157        smp_mb__after_atomic_inc();
158    }
159
160    /* Invalidate all timestamps while vblank irq's are off. */
161    clear_vblank_timestamps(dev, crtc);
162
163    spin_unlock_irqrestore(&dev->vblank_time_lock, irqflags);
164}
165
166static void vblank_disable_fn(unsigned long arg)
167{
168    struct drm_device *dev = (struct drm_device *)arg;
169    unsigned long irqflags;
170    int i;
171
172    if (!dev->vblank_disable_allowed)
173        return;
174
175    for (i = 0; i < dev->num_crtcs; i++) {
176        spin_lock_irqsave(&dev->vbl_lock, irqflags);
177        if (atomic_read(&dev->vblank_refcount[i]) == 0 &&
178            dev->vblank_enabled[i]) {
179            DRM_DEBUG("disabling vblank on crtc %d\n", i);
180            vblank_disable_and_save(dev, i);
181        }
182        spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
183    }
184}
185
186void drm_vblank_cleanup(struct drm_device *dev)
187{
188    /* Bail if the driver didn't call drm_vblank_init() */
189    if (dev->num_crtcs == 0)
190        return;
191
192    del_timer_sync(&dev->vblank_disable_timer);
193
194    vblank_disable_fn((unsigned long)dev);
195
196    kfree(dev->vbl_queue);
197    kfree(dev->_vblank_count);
198    kfree(dev->vblank_refcount);
199    kfree(dev->vblank_enabled);
200    kfree(dev->last_vblank);
201    kfree(dev->last_vblank_wait);
202    kfree(dev->vblank_inmodeset);
203    kfree(dev->_vblank_time);
204
205    dev->num_crtcs = 0;
206}
207EXPORT_SYMBOL(drm_vblank_cleanup);
208
209int drm_vblank_init(struct drm_device *dev, int num_crtcs)
210{
211    int i, ret = -ENOMEM;
212
213    setup_timer(&dev->vblank_disable_timer, vblank_disable_fn,
214            (unsigned long)dev);
215    spin_lock_init(&dev->vbl_lock);
216    spin_lock_init(&dev->vblank_time_lock);
217
218    dev->num_crtcs = num_crtcs;
219
220    dev->vbl_queue = kmalloc(sizeof(wait_queue_head_t) * num_crtcs,
221                 GFP_KERNEL);
222    if (!dev->vbl_queue)
223        goto err;
224
225    dev->_vblank_count = kmalloc(sizeof(atomic_t) * num_crtcs, GFP_KERNEL);
226    if (!dev->_vblank_count)
227        goto err;
228
229    dev->vblank_refcount = kmalloc(sizeof(atomic_t) * num_crtcs,
230                       GFP_KERNEL);
231    if (!dev->vblank_refcount)
232        goto err;
233
234    dev->vblank_enabled = kcalloc(num_crtcs, sizeof(int), GFP_KERNEL);
235    if (!dev->vblank_enabled)
236        goto err;
237
238    dev->last_vblank = kcalloc(num_crtcs, sizeof(u32), GFP_KERNEL);
239    if (!dev->last_vblank)
240        goto err;
241
242    dev->last_vblank_wait = kcalloc(num_crtcs, sizeof(u32), GFP_KERNEL);
243    if (!dev->last_vblank_wait)
244        goto err;
245
246    dev->vblank_inmodeset = kcalloc(num_crtcs, sizeof(int), GFP_KERNEL);
247    if (!dev->vblank_inmodeset)
248        goto err;
249
250    dev->_vblank_time = kcalloc(num_crtcs * DRM_VBLANKTIME_RBSIZE,
251                    sizeof(struct timeval), GFP_KERNEL);
252    if (!dev->_vblank_time)
253        goto err;
254
255    DRM_INFO("Supports vblank timestamp caching Rev 1 (10.10.2010).\n");
256
257    /* Driver specific high-precision vblank timestamping supported? */
258    if (dev->driver->get_vblank_timestamp)
259        DRM_INFO("Driver supports precise vblank timestamp query.\n");
260    else
261        DRM_INFO("No driver support for vblank timestamp query.\n");
262
263    /* Zero per-crtc vblank stuff */
264    for (i = 0; i < num_crtcs; i++) {
265        init_waitqueue_head(&dev->vbl_queue[i]);
266        atomic_set(&dev->_vblank_count[i], 0);
267        atomic_set(&dev->vblank_refcount[i], 0);
268    }
269
270    dev->vblank_disable_allowed = 0;
271    return 0;
272
273err:
274    drm_vblank_cleanup(dev);
275    return ret;
276}
277EXPORT_SYMBOL(drm_vblank_init);
278
279static void drm_irq_vgaarb_nokms(void *cookie, bool state)
280{
281    struct drm_device *dev = cookie;
282
283    if (dev->driver->vgaarb_irq) {
284        dev->driver->vgaarb_irq(dev, state);
285        return;
286    }
287
288    if (!dev->irq_enabled)
289        return;
290
291    if (state) {
292        if (dev->driver->irq_uninstall)
293            dev->driver->irq_uninstall(dev);
294    } else {
295        if (dev->driver->irq_preinstall)
296            dev->driver->irq_preinstall(dev);
297        if (dev->driver->irq_postinstall)
298            dev->driver->irq_postinstall(dev);
299    }
300}
301
302/**
303 * Install IRQ handler.
304 *
305 * \param dev DRM device.
306 *
307 * Initializes the IRQ related data. Installs the handler, calling the driver
308 * \c irq_preinstall() and \c irq_postinstall() functions
309 * before and after the installation.
310 */
311int drm_irq_install(struct drm_device *dev)
312{
313    int ret;
314    unsigned long sh_flags = 0;
315    char *irqname;
316
317    if (!drm_core_check_feature(dev, DRIVER_HAVE_IRQ))
318        return -EINVAL;
319
320    if (drm_dev_to_irq(dev) == 0)
321        return -EINVAL;
322
323    mutex_lock(&dev->struct_mutex);
324
325    /* Driver must have been initialized */
326    if (!dev->dev_private) {
327        mutex_unlock(&dev->struct_mutex);
328        return -EINVAL;
329    }
330
331    if (dev->irq_enabled) {
332        mutex_unlock(&dev->struct_mutex);
333        return -EBUSY;
334    }
335    dev->irq_enabled = 1;
336    mutex_unlock(&dev->struct_mutex);
337
338    DRM_DEBUG("irq=%d\n", drm_dev_to_irq(dev));
339
340    /* Before installing handler */
341    if (dev->driver->irq_preinstall)
342        dev->driver->irq_preinstall(dev);
343
344    /* Install handler */
345    if (drm_core_check_feature(dev, DRIVER_IRQ_SHARED))
346        sh_flags = IRQF_SHARED;
347
348    if (dev->devname)
349        irqname = dev->devname;
350    else
351        irqname = dev->driver->name;
352
353    ret = request_irq(drm_dev_to_irq(dev), dev->driver->irq_handler,
354              sh_flags, irqname, dev);
355
356    if (ret < 0) {
357        mutex_lock(&dev->struct_mutex);
358        dev->irq_enabled = 0;
359        mutex_unlock(&dev->struct_mutex);
360        return ret;
361    }
362
363    if (!drm_core_check_feature(dev, DRIVER_MODESET))
364        vga_client_register(dev->pdev, (void *)dev, drm_irq_vgaarb_nokms, NULL);
365
366    /* After installing handler */
367    if (dev->driver->irq_postinstall)
368        ret = dev->driver->irq_postinstall(dev);
369
370    if (ret < 0) {
371        mutex_lock(&dev->struct_mutex);
372        dev->irq_enabled = 0;
373        mutex_unlock(&dev->struct_mutex);
374        if (!drm_core_check_feature(dev, DRIVER_MODESET))
375            vga_client_register(dev->pdev, NULL, NULL, NULL);
376        free_irq(drm_dev_to_irq(dev), dev);
377    }
378
379    return ret;
380}
381EXPORT_SYMBOL(drm_irq_install);
382
383/**
384 * Uninstall the IRQ handler.
385 *
386 * \param dev DRM device.
387 *
388 * Calls the driver's \c irq_uninstall() function, and stops the irq.
389 */
390int drm_irq_uninstall(struct drm_device *dev)
391{
392    unsigned long irqflags;
393    int irq_enabled, i;
394
395    if (!drm_core_check_feature(dev, DRIVER_HAVE_IRQ))
396        return -EINVAL;
397
398    mutex_lock(&dev->struct_mutex);
399    irq_enabled = dev->irq_enabled;
400    dev->irq_enabled = 0;
401    mutex_unlock(&dev->struct_mutex);
402
403    /*
404     * Wake up any waiters so they don't hang.
405     */
406    if (dev->num_crtcs) {
407        spin_lock_irqsave(&dev->vbl_lock, irqflags);
408        for (i = 0; i < dev->num_crtcs; i++) {
409            DRM_WAKEUP(&dev->vbl_queue[i]);
410            dev->vblank_enabled[i] = 0;
411            dev->last_vblank[i] =
412                dev->driver->get_vblank_counter(dev, i);
413        }
414        spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
415    }
416
417    if (!irq_enabled)
418        return -EINVAL;
419
420    DRM_DEBUG("irq=%d\n", drm_dev_to_irq(dev));
421
422    if (!drm_core_check_feature(dev, DRIVER_MODESET))
423        vga_client_register(dev->pdev, NULL, NULL, NULL);
424
425    if (dev->driver->irq_uninstall)
426        dev->driver->irq_uninstall(dev);
427
428    free_irq(drm_dev_to_irq(dev), dev);
429
430    return 0;
431}
432EXPORT_SYMBOL(drm_irq_uninstall);
433
434/**
435 * IRQ control ioctl.
436 *
437 * \param inode device inode.
438 * \param file_priv DRM file private.
439 * \param cmd command.
440 * \param arg user argument, pointing to a drm_control structure.
441 * \return zero on success or a negative number on failure.
442 *
443 * Calls irq_install() or irq_uninstall() according to \p arg.
444 */
445int drm_control(struct drm_device *dev, void *data,
446        struct drm_file *file_priv)
447{
448    struct drm_control *ctl = data;
449
450    /* if we haven't irq we fallback for compatibility reasons -
451     * this used to be a separate function in drm_dma.h
452     */
453
454
455    switch (ctl->func) {
456    case DRM_INST_HANDLER:
457        if (!drm_core_check_feature(dev, DRIVER_HAVE_IRQ))
458            return 0;
459        if (drm_core_check_feature(dev, DRIVER_MODESET))
460            return 0;
461        if (dev->if_version < DRM_IF_VERSION(1, 2) &&
462            ctl->irq != drm_dev_to_irq(dev))
463            return -EINVAL;
464        return drm_irq_install(dev);
465    case DRM_UNINST_HANDLER:
466        if (!drm_core_check_feature(dev, DRIVER_HAVE_IRQ))
467            return 0;
468        if (drm_core_check_feature(dev, DRIVER_MODESET))
469            return 0;
470        return drm_irq_uninstall(dev);
471    default:
472        return -EINVAL;
473    }
474}
475
476/**
477 * drm_calc_timestamping_constants - Calculate and
478 * store various constants which are later needed by
479 * vblank and swap-completion timestamping, e.g, by
480 * drm_calc_vbltimestamp_from_scanoutpos().
481 * They are derived from crtc's true scanout timing,
482 * so they take things like panel scaling or other
483 * adjustments into account.
484 *
485 * @crtc drm_crtc whose timestamp constants should be updated.
486 *
487 */
488void drm_calc_timestamping_constants(struct drm_crtc *crtc)
489{
490    s64 linedur_ns = 0, pixeldur_ns = 0, framedur_ns = 0;
491    u64 dotclock;
492
493    /* Dot clock in Hz: */
494    dotclock = (u64) crtc->hwmode.clock * 1000;
495
496    /* Fields of interlaced scanout modes are only halve a frame duration.
497     * Double the dotclock to get halve the frame-/line-/pixelduration.
498     */
499    if (crtc->hwmode.flags & DRM_MODE_FLAG_INTERLACE)
500        dotclock *= 2;
501
502    /* Valid dotclock? */
503    if (dotclock > 0) {
504        /* Convert scanline length in pixels and video dot clock to
505         * line duration, frame duration and pixel duration in
506         * nanoseconds:
507         */
508        pixeldur_ns = (s64) div64_u64(1000000000, dotclock);
509        linedur_ns = (s64) div64_u64(((u64) crtc->hwmode.crtc_htotal *
510                          1000000000), dotclock);
511        framedur_ns = (s64) crtc->hwmode.crtc_vtotal * linedur_ns;
512    } else
513        DRM_ERROR("crtc %d: Can't calculate constants, dotclock = 0!\n",
514              crtc->base.id);
515
516    crtc->pixeldur_ns = pixeldur_ns;
517    crtc->linedur_ns = linedur_ns;
518    crtc->framedur_ns = framedur_ns;
519
520    DRM_DEBUG("crtc %d: hwmode: htotal %d, vtotal %d, vdisplay %d\n",
521          crtc->base.id, crtc->hwmode.crtc_htotal,
522          crtc->hwmode.crtc_vtotal, crtc->hwmode.crtc_vdisplay);
523    DRM_DEBUG("crtc %d: clock %d kHz framedur %d linedur %d, pixeldur %d\n",
524          crtc->base.id, (int) dotclock/1000, (int) framedur_ns,
525          (int) linedur_ns, (int) pixeldur_ns);
526}
527EXPORT_SYMBOL(drm_calc_timestamping_constants);
528
529/**
530 * drm_calc_vbltimestamp_from_scanoutpos - helper routine for kms
531 * drivers. Implements calculation of exact vblank timestamps from
532 * given drm_display_mode timings and current video scanout position
533 * of a crtc. This can be called from within get_vblank_timestamp()
534 * implementation of a kms driver to implement the actual timestamping.
535 *
536 * Should return timestamps conforming to the OML_sync_control OpenML
537 * extension specification. The timestamp corresponds to the end of
538 * the vblank interval, aka start of scanout of topmost-leftmost display
539 * pixel in the following video frame.
540 *
541 * Requires support for optional dev->driver->get_scanout_position()
542 * in kms driver, plus a bit of setup code to provide a drm_display_mode
543 * that corresponds to the true scanout timing.
544 *
545 * The current implementation only handles standard video modes. It
546 * returns as no operation if a doublescan or interlaced video mode is
547 * active. Higher level code is expected to handle this.
548 *
549 * @dev: DRM device.
550 * @crtc: Which crtc's vblank timestamp to retrieve.
551 * @max_error: Desired maximum allowable error in timestamps (nanosecs).
552 * On return contains true maximum error of timestamp.
553 * @vblank_time: Pointer to struct timeval which should receive the timestamp.
554 * @flags: Flags to pass to driver:
555 * 0 = Default.
556 * DRM_CALLED_FROM_VBLIRQ = If function is called from vbl irq handler.
557 * @refcrtc: drm_crtc* of crtc which defines scanout timing.
558 *
559 * Returns negative value on error, failure or if not supported in current
560 * video mode:
561 *
562 * -EINVAL - Invalid crtc.
563 * -EAGAIN - Temporary unavailable, e.g., called before initial modeset.
564 * -ENOTSUPP - Function not supported in current display mode.
565 * -EIO - Failed, e.g., due to failed scanout position query.
566 *
567 * Returns or'ed positive status flags on success:
568 *
569 * DRM_VBLANKTIME_SCANOUTPOS_METHOD - Signal this method used for timestamping.
570 * DRM_VBLANKTIME_INVBL - Timestamp taken while scanout was in vblank interval.
571 *
572 */
573int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, int crtc,
574                      int *max_error,
575                      struct timeval *vblank_time,
576                      unsigned flags,
577                      struct drm_crtc *refcrtc)
578{
579    struct timeval stime, raw_time;
580    struct drm_display_mode *mode;
581    int vbl_status, vtotal, vdisplay;
582    int vpos, hpos, i;
583    s64 framedur_ns, linedur_ns, pixeldur_ns, delta_ns, duration_ns;
584    bool invbl;
585
586    if (crtc < 0 || crtc >= dev->num_crtcs) {
587        DRM_ERROR("Invalid crtc %d\n", crtc);
588        return -EINVAL;
589    }
590
591    /* Scanout position query not supported? Should not happen. */
592    if (!dev->driver->get_scanout_position) {
593        DRM_ERROR("Called from driver w/o get_scanout_position()!?\n");
594        return -EIO;
595    }
596
597    mode = &refcrtc->hwmode;
598    vtotal = mode->crtc_vtotal;
599    vdisplay = mode->crtc_vdisplay;
600
601    /* Durations of frames, lines, pixels in nanoseconds. */
602    framedur_ns = refcrtc->framedur_ns;
603    linedur_ns = refcrtc->linedur_ns;
604    pixeldur_ns = refcrtc->pixeldur_ns;
605
606    /* If mode timing undefined, just return as no-op:
607     * Happens during initial modesetting of a crtc.
608     */
609    if (vtotal <= 0 || vdisplay <= 0 || framedur_ns == 0) {
610        DRM_DEBUG("crtc %d: Noop due to uninitialized mode.\n", crtc);
611        return -EAGAIN;
612    }
613
614    /* Get current scanout position with system timestamp.
615     * Repeat query up to DRM_TIMESTAMP_MAXRETRIES times
616     * if single query takes longer than max_error nanoseconds.
617     *
618     * This guarantees a tight bound on maximum error if
619     * code gets preempted or delayed for some reason.
620     */
621    for (i = 0; i < DRM_TIMESTAMP_MAXRETRIES; i++) {
622        /* Disable preemption to make it very likely to
623         * succeed in the first iteration even on PREEMPT_RT kernel.
624         */
625        preempt_disable();
626
627        /* Get system timestamp before query. */
628        do_gettimeofday(&stime);
629
630        /* Get vertical and horizontal scanout pos. vpos, hpos. */
631        vbl_status = dev->driver->get_scanout_position(dev, crtc, &vpos, &hpos);
632
633        /* Get system timestamp after query. */
634        do_gettimeofday(&raw_time);
635
636        preempt_enable();
637
638        /* Return as no-op if scanout query unsupported or failed. */
639        if (!(vbl_status & DRM_SCANOUTPOS_VALID)) {
640            DRM_DEBUG("crtc %d : scanoutpos query failed [%d].\n",
641                  crtc, vbl_status);
642            return -EIO;
643        }
644
645        duration_ns = timeval_to_ns(&raw_time) - timeval_to_ns(&stime);
646
647        /* Accept result with < max_error nsecs timing uncertainty. */
648        if (duration_ns <= (s64) *max_error)
649            break;
650    }
651
652    /* Noisy system timing? */
653    if (i == DRM_TIMESTAMP_MAXRETRIES) {
654        DRM_DEBUG("crtc %d: Noisy timestamp %d us > %d us [%d reps].\n",
655              crtc, (int) duration_ns/1000, *max_error/1000, i);
656    }
657
658    /* Return upper bound of timestamp precision error. */
659    *max_error = (int) duration_ns;
660
661    /* Check if in vblank area:
662     * vpos is >=0 in video scanout area, but negative
663     * within vblank area, counting down the number of lines until
664     * start of scanout.
665     */
666    invbl = vbl_status & DRM_SCANOUTPOS_INVBL;
667
668    /* Convert scanout position into elapsed time at raw_time query
669     * since start of scanout at first display scanline. delta_ns
670     * can be negative if start of scanout hasn't happened yet.
671     */
672    delta_ns = (s64) vpos * linedur_ns + (s64) hpos * pixeldur_ns;
673
674    /* Is vpos outside nominal vblank area, but less than
675     * 1/100 of a frame height away from start of vblank?
676     * If so, assume this isn't a massively delayed vblank
677     * interrupt, but a vblank interrupt that fired a few
678     * microseconds before true start of vblank. Compensate
679     * by adding a full frame duration to the final timestamp.
680     * Happens, e.g., on ATI R500, R600.
681     *
682     * We only do this if DRM_CALLED_FROM_VBLIRQ.
683     */
684    if ((flags & DRM_CALLED_FROM_VBLIRQ) && !invbl &&
685        ((vdisplay - vpos) < vtotal / 100)) {
686        delta_ns = delta_ns - framedur_ns;
687
688        /* Signal this correction as "applied". */
689        vbl_status |= 0x8;
690    }
691
692    /* Subtract time delta from raw timestamp to get final
693     * vblank_time timestamp for end of vblank.
694     */
695    *vblank_time = ns_to_timeval(timeval_to_ns(&raw_time) - delta_ns);
696
697    DRM_DEBUG("crtc %d : v %d p(%d,%d)@ %ld.%ld -> %ld.%ld [e %d us, %d rep]\n",
698          crtc, (int)vbl_status, hpos, vpos,
699          (long)raw_time.tv_sec, (long)raw_time.tv_usec,
700          (long)vblank_time->tv_sec, (long)vblank_time->tv_usec,
701          (int)duration_ns/1000, i);
702
703    vbl_status = DRM_VBLANKTIME_SCANOUTPOS_METHOD;
704    if (invbl)
705        vbl_status |= DRM_VBLANKTIME_INVBL;
706
707    return vbl_status;
708}
709EXPORT_SYMBOL(drm_calc_vbltimestamp_from_scanoutpos);
710
711/**
712 * drm_get_last_vbltimestamp - retrieve raw timestamp for the most recent
713 * vblank interval.
714 *
715 * @dev: DRM device
716 * @crtc: which crtc's vblank timestamp to retrieve
717 * @tvblank: Pointer to target struct timeval which should receive the timestamp
718 * @flags: Flags to pass to driver:
719 * 0 = Default.
720 * DRM_CALLED_FROM_VBLIRQ = If function is called from vbl irq handler.
721 *
722 * Fetches the system timestamp corresponding to the time of the most recent
723 * vblank interval on specified crtc. May call into kms-driver to
724 * compute the timestamp with a high-precision GPU specific method.
725 *
726 * Returns zero if timestamp originates from uncorrected do_gettimeofday()
727 * call, i.e., it isn't very precisely locked to the true vblank.
728 *
729 * Returns non-zero if timestamp is considered to be very precise.
730 */
731u32 drm_get_last_vbltimestamp(struct drm_device *dev, int crtc,
732                  struct timeval *tvblank, unsigned flags)
733{
734    int ret;
735
736    /* Define requested maximum error on timestamps (nanoseconds). */
737    int max_error = (int) drm_timestamp_precision * 1000;
738
739    /* Query driver if possible and precision timestamping enabled. */
740    if (dev->driver->get_vblank_timestamp && (max_error > 0)) {
741        ret = dev->driver->get_vblank_timestamp(dev, crtc, &max_error,
742                            tvblank, flags);
743        if (ret > 0)
744            return (u32) ret;
745    }
746
747    /* GPU high precision timestamp query unsupported or failed.
748     * Return gettimeofday timestamp as best estimate.
749     */
750    do_gettimeofday(tvblank);
751
752    return 0;
753}
754EXPORT_SYMBOL(drm_get_last_vbltimestamp);
755
756/**
757 * drm_vblank_count - retrieve "cooked" vblank counter value
758 * @dev: DRM device
759 * @crtc: which counter to retrieve
760 *
761 * Fetches the "cooked" vblank count value that represents the number of
762 * vblank events since the system was booted, including lost events due to
763 * modesetting activity.
764 */
765u32 drm_vblank_count(struct drm_device *dev, int crtc)
766{
767    return atomic_read(&dev->_vblank_count[crtc]);
768}
769EXPORT_SYMBOL(drm_vblank_count);
770
771/**
772 * drm_vblank_count_and_time - retrieve "cooked" vblank counter value
773 * and the system timestamp corresponding to that vblank counter value.
774 *
775 * @dev: DRM device
776 * @crtc: which counter to retrieve
777 * @vblanktime: Pointer to struct timeval to receive the vblank timestamp.
778 *
779 * Fetches the "cooked" vblank count value that represents the number of
780 * vblank events since the system was booted, including lost events due to
781 * modesetting activity. Returns corresponding system timestamp of the time
782 * of the vblank interval that corresponds to the current value vblank counter
783 * value.
784 */
785u32 drm_vblank_count_and_time(struct drm_device *dev, int crtc,
786                  struct timeval *vblanktime)
787{
788    u32 cur_vblank;
789
790    /* Read timestamp from slot of _vblank_time ringbuffer
791     * that corresponds to current vblank count. Retry if
792     * count has incremented during readout. This works like
793     * a seqlock.
794     */
795    do {
796        cur_vblank = atomic_read(&dev->_vblank_count[crtc]);
797        *vblanktime = vblanktimestamp(dev, crtc, cur_vblank);
798        smp_rmb();
799    } while (cur_vblank != atomic_read(&dev->_vblank_count[crtc]));
800
801    return cur_vblank;
802}
803EXPORT_SYMBOL(drm_vblank_count_and_time);
804
805/**
806 * drm_update_vblank_count - update the master vblank counter
807 * @dev: DRM device
808 * @crtc: counter to update
809 *
810 * Call back into the driver to update the appropriate vblank counter
811 * (specified by @crtc). Deal with wraparound, if it occurred, and
812 * update the last read value so we can deal with wraparound on the next
813 * call if necessary.
814 *
815 * Only necessary when going from off->on, to account for frames we
816 * didn't get an interrupt for.
817 *
818 * Note: caller must hold dev->vbl_lock since this reads & writes
819 * device vblank fields.
820 */
821static void drm_update_vblank_count(struct drm_device *dev, int crtc)
822{
823    u32 cur_vblank, diff, tslot, rc;
824    struct timeval t_vblank;
825
826    /*
827     * Interrupts were disabled prior to this call, so deal with counter
828     * wrap if needed.
829     * NOTE! It's possible we lost a full dev->max_vblank_count events
830     * here if the register is small or we had vblank interrupts off for
831     * a long time.
832     *
833     * We repeat the hardware vblank counter & timestamp query until
834     * we get consistent results. This to prevent races between gpu
835     * updating its hardware counter while we are retrieving the
836     * corresponding vblank timestamp.
837     */
838    do {
839        cur_vblank = dev->driver->get_vblank_counter(dev, crtc);
840        rc = drm_get_last_vbltimestamp(dev, crtc, &t_vblank, 0);
841    } while (cur_vblank != dev->driver->get_vblank_counter(dev, crtc));
842
843    /* Deal with counter wrap */
844    diff = cur_vblank - dev->last_vblank[crtc];
845    if (cur_vblank < dev->last_vblank[crtc]) {
846        diff += dev->max_vblank_count;
847
848        DRM_DEBUG("last_vblank[%d]=0x%x, cur_vblank=0x%x => diff=0x%x\n",
849              crtc, dev->last_vblank[crtc], cur_vblank, diff);
850    }
851
852    DRM_DEBUG("enabling vblank interrupts on crtc %d, missed %d\n",
853          crtc, diff);
854
855    /* Reinitialize corresponding vblank timestamp if high-precision query
856     * available. Skip this step if query unsupported or failed. Will
857     * reinitialize delayed at next vblank interrupt in that case.
858     */
859    if (rc) {
860        tslot = atomic_read(&dev->_vblank_count[crtc]) + diff;
861        vblanktimestamp(dev, crtc, tslot) = t_vblank;
862    }
863
864    smp_mb__before_atomic_inc();
865    atomic_add(diff, &dev->_vblank_count[crtc]);
866    smp_mb__after_atomic_inc();
867}
868
869/**
870 * drm_vblank_get - get a reference count on vblank events
871 * @dev: DRM device
872 * @crtc: which CRTC to own
873 *
874 * Acquire a reference count on vblank events to avoid having them disabled
875 * while in use.
876 *
877 * RETURNS
878 * Zero on success, nonzero on failure.
879 */
880int drm_vblank_get(struct drm_device *dev, int crtc)
881{
882    unsigned long irqflags, irqflags2;
883    int ret = 0;
884
885    spin_lock_irqsave(&dev->vbl_lock, irqflags);
886    /* Going from 0->1 means we have to enable interrupts again */
887    if (atomic_add_return(1, &dev->vblank_refcount[crtc]) == 1) {
888        spin_lock_irqsave(&dev->vblank_time_lock, irqflags2);
889        if (!dev->vblank_enabled[crtc]) {
890            /* Enable vblank irqs under vblank_time_lock protection.
891             * All vblank count & timestamp updates are held off
892             * until we are done reinitializing master counter and
893             * timestamps. Filtercode in drm_handle_vblank() will
894             * prevent double-accounting of same vblank interval.
895             */
896            ret = dev->driver->enable_vblank(dev, crtc);
897            DRM_DEBUG("enabling vblank on crtc %d, ret: %d\n",
898                  crtc, ret);
899            if (ret)
900                atomic_dec(&dev->vblank_refcount[crtc]);
901            else {
902                dev->vblank_enabled[crtc] = 1;
903                drm_update_vblank_count(dev, crtc);
904            }
905        }
906        spin_unlock_irqrestore(&dev->vblank_time_lock, irqflags2);
907    } else {
908        if (!dev->vblank_enabled[crtc]) {
909            atomic_dec(&dev->vblank_refcount[crtc]);
910            ret = -EINVAL;
911        }
912    }
913    spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
914
915    return ret;
916}
917EXPORT_SYMBOL(drm_vblank_get);
918
919/**
920 * drm_vblank_put - give up ownership of vblank events
921 * @dev: DRM device
922 * @crtc: which counter to give up
923 *
924 * Release ownership of a given vblank counter, turning off interrupts
925 * if possible. Disable interrupts after drm_vblank_offdelay milliseconds.
926 */
927void drm_vblank_put(struct drm_device *dev, int crtc)
928{
929    BUG_ON(atomic_read(&dev->vblank_refcount[crtc]) == 0);
930
931    /* Last user schedules interrupt disable */
932    if (atomic_dec_and_test(&dev->vblank_refcount[crtc]) &&
933        (drm_vblank_offdelay > 0))
934        mod_timer(&dev->vblank_disable_timer,
935              jiffies + ((drm_vblank_offdelay * DRM_HZ)/1000));
936}
937EXPORT_SYMBOL(drm_vblank_put);
938
939void drm_vblank_off(struct drm_device *dev, int crtc)
940{
941    struct drm_pending_vblank_event *e, *t;
942    struct timeval now;
943    unsigned long irqflags;
944    unsigned int seq;
945
946    spin_lock_irqsave(&dev->vbl_lock, irqflags);
947    vblank_disable_and_save(dev, crtc);
948    DRM_WAKEUP(&dev->vbl_queue[crtc]);
949
950    /* Send any queued vblank events, lest the natives grow disquiet */
951    seq = drm_vblank_count_and_time(dev, crtc, &now);
952    list_for_each_entry_safe(e, t, &dev->vblank_event_list, base.link) {
953        if (e->pipe != crtc)
954            continue;
955        DRM_DEBUG("Sending premature vblank event on disable: \
956              wanted %d, current %d\n",
957              e->event.sequence, seq);
958
959        e->event.sequence = seq;
960        e->event.tv_sec = now.tv_sec;
961        e->event.tv_usec = now.tv_usec;
962        drm_vblank_put(dev, e->pipe);
963        list_move_tail(&e->base.link, &e->base.file_priv->event_list);
964        wake_up_interruptible(&e->base.file_priv->event_wait);
965        trace_drm_vblank_event_delivered(e->base.pid, e->pipe,
966                         e->event.sequence);
967    }
968
969    spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
970}
971EXPORT_SYMBOL(drm_vblank_off);
972
973/**
974 * drm_vblank_pre_modeset - account for vblanks across mode sets
975 * @dev: DRM device
976 * @crtc: CRTC in question
977 *
978 * Account for vblank events across mode setting events, which will likely
979 * reset the hardware frame counter.
980 */
981void drm_vblank_pre_modeset(struct drm_device *dev, int crtc)
982{
983    /* vblank is not initialized (IRQ not installed ?) */
984    if (!dev->num_crtcs)
985        return;
986    /*
987     * To avoid all the problems that might happen if interrupts
988     * were enabled/disabled around or between these calls, we just
989     * have the kernel take a reference on the CRTC (just once though
990     * to avoid corrupting the count if multiple, mismatch calls occur),
991     * so that interrupts remain enabled in the interim.
992     */
993    if (!dev->vblank_inmodeset[crtc]) {
994        dev->vblank_inmodeset[crtc] = 0x1;
995        if (drm_vblank_get(dev, crtc) == 0)
996            dev->vblank_inmodeset[crtc] |= 0x2;
997    }
998}
999EXPORT_SYMBOL(drm_vblank_pre_modeset);
1000
1001void drm_vblank_post_modeset(struct drm_device *dev, int crtc)
1002{
1003    unsigned long irqflags;
1004
1005    if (dev->vblank_inmodeset[crtc]) {
1006        spin_lock_irqsave(&dev->vbl_lock, irqflags);
1007        dev->vblank_disable_allowed = 1;
1008        spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
1009
1010        if (dev->vblank_inmodeset[crtc] & 0x2)
1011            drm_vblank_put(dev, crtc);
1012
1013        dev->vblank_inmodeset[crtc] = 0;
1014    }
1015}
1016EXPORT_SYMBOL(drm_vblank_post_modeset);
1017
1018/**
1019 * drm_modeset_ctl - handle vblank event counter changes across mode switch
1020 * @DRM_IOCTL_ARGS: standard ioctl arguments
1021 *
1022 * Applications should call the %_DRM_PRE_MODESET and %_DRM_POST_MODESET
1023 * ioctls around modesetting so that any lost vblank events are accounted for.
1024 *
1025 * Generally the counter will reset across mode sets. If interrupts are
1026 * enabled around this call, we don't have to do anything since the counter
1027 * will have already been incremented.
1028 */
1029int drm_modeset_ctl(struct drm_device *dev, void *data,
1030            struct drm_file *file_priv)
1031{
1032    struct drm_modeset_ctl *modeset = data;
1033    unsigned int crtc;
1034
1035    /* If drm_vblank_init() hasn't been called yet, just no-op */
1036    if (!dev->num_crtcs)
1037        return 0;
1038
1039    /* KMS drivers handle this internally */
1040    if (drm_core_check_feature(dev, DRIVER_MODESET))
1041        return 0;
1042
1043    crtc = modeset->crtc;
1044    if (crtc >= dev->num_crtcs)
1045        return -EINVAL;
1046
1047    switch (modeset->cmd) {
1048    case _DRM_PRE_MODESET:
1049        drm_vblank_pre_modeset(dev, crtc);
1050        break;
1051    case _DRM_POST_MODESET:
1052        drm_vblank_post_modeset(dev, crtc);
1053        break;
1054    default:
1055        return -EINVAL;
1056    }
1057
1058    return 0;
1059}
1060
1061static int drm_queue_vblank_event(struct drm_device *dev, int pipe,
1062                  union drm_wait_vblank *vblwait,
1063                  struct drm_file *file_priv)
1064{
1065    struct drm_pending_vblank_event *e;
1066    struct timeval now;
1067    unsigned long flags;
1068    unsigned int seq;
1069    int ret;
1070
1071    e = kzalloc(sizeof *e, GFP_KERNEL);
1072    if (e == NULL) {
1073        ret = -ENOMEM;
1074        goto err_put;
1075    }
1076
1077    e->pipe = pipe;
1078    e->base.pid = current->pid;
1079    e->event.base.type = DRM_EVENT_VBLANK;
1080    e->event.base.length = sizeof e->event;
1081    e->event.user_data = vblwait->request.signal;
1082    e->base.event = &e->event.base;
1083    e->base.file_priv = file_priv;
1084    e->base.destroy = (void (*) (struct drm_pending_event *)) kfree;
1085
1086    spin_lock_irqsave(&dev->event_lock, flags);
1087
1088    if (file_priv->event_space < sizeof e->event) {
1089        ret = -EBUSY;
1090        goto err_unlock;
1091    }
1092
1093    file_priv->event_space -= sizeof e->event;
1094    seq = drm_vblank_count_and_time(dev, pipe, &now);
1095
1096    if ((vblwait->request.type & _DRM_VBLANK_NEXTONMISS) &&
1097        (seq - vblwait->request.sequence) <= (1 << 23)) {
1098        vblwait->request.sequence = seq + 1;
1099        vblwait->reply.sequence = vblwait->request.sequence;
1100    }
1101
1102    DRM_DEBUG("event on vblank count %d, current %d, crtc %d\n",
1103          vblwait->request.sequence, seq, pipe);
1104
1105    trace_drm_vblank_event_queued(current->pid, pipe,
1106                      vblwait->request.sequence);
1107
1108    e->event.sequence = vblwait->request.sequence;
1109    if ((seq - vblwait->request.sequence) <= (1 << 23)) {
1110        e->event.sequence = seq;
1111        e->event.tv_sec = now.tv_sec;
1112        e->event.tv_usec = now.tv_usec;
1113        drm_vblank_put(dev, pipe);
1114        list_add_tail(&e->base.link, &e->base.file_priv->event_list);
1115        wake_up_interruptible(&e->base.file_priv->event_wait);
1116        vblwait->reply.sequence = seq;
1117        trace_drm_vblank_event_delivered(current->pid, pipe,
1118                         vblwait->request.sequence);
1119    } else {
1120        /* drm_handle_vblank_events will call drm_vblank_put */
1121        list_add_tail(&e->base.link, &dev->vblank_event_list);
1122        vblwait->reply.sequence = vblwait->request.sequence;
1123    }
1124
1125    spin_unlock_irqrestore(&dev->event_lock, flags);
1126
1127    return 0;
1128
1129err_unlock:
1130    spin_unlock_irqrestore(&dev->event_lock, flags);
1131    kfree(e);
1132err_put:
1133    drm_vblank_put(dev, pipe);
1134    return ret;
1135}
1136
1137/**
1138 * Wait for VBLANK.
1139 *
1140 * \param inode device inode.
1141 * \param file_priv DRM file private.
1142 * \param cmd command.
1143 * \param data user argument, pointing to a drm_wait_vblank structure.
1144 * \return zero on success or a negative number on failure.
1145 *
1146 * This function enables the vblank interrupt on the pipe requested, then
1147 * sleeps waiting for the requested sequence number to occur, and drops
1148 * the vblank interrupt refcount afterwards. (vblank irq disable follows that
1149 * after a timeout with no further vblank waits scheduled).
1150 */
1151int drm_wait_vblank(struct drm_device *dev, void *data,
1152            struct drm_file *file_priv)
1153{
1154    union drm_wait_vblank *vblwait = data;
1155    int ret;
1156    unsigned int flags, seq, crtc, high_crtc;
1157
1158    if ((!drm_dev_to_irq(dev)) || (!dev->irq_enabled))
1159        return -EINVAL;
1160
1161    if (vblwait->request.type & _DRM_VBLANK_SIGNAL)
1162        return -EINVAL;
1163
1164    if (vblwait->request.type &
1165        ~(_DRM_VBLANK_TYPES_MASK | _DRM_VBLANK_FLAGS_MASK |
1166          _DRM_VBLANK_HIGH_CRTC_MASK)) {
1167        DRM_ERROR("Unsupported type value 0x%x, supported mask 0x%x\n",
1168              vblwait->request.type,
1169              (_DRM_VBLANK_TYPES_MASK | _DRM_VBLANK_FLAGS_MASK |
1170               _DRM_VBLANK_HIGH_CRTC_MASK));
1171        return -EINVAL;
1172    }
1173
1174    flags = vblwait->request.type & _DRM_VBLANK_FLAGS_MASK;
1175    high_crtc = (vblwait->request.type & _DRM_VBLANK_HIGH_CRTC_MASK);
1176    if (high_crtc)
1177        crtc = high_crtc >> _DRM_VBLANK_HIGH_CRTC_SHIFT;
1178    else
1179        crtc = flags & _DRM_VBLANK_SECONDARY ? 1 : 0;
1180    if (crtc >= dev->num_crtcs)
1181        return -EINVAL;
1182
1183    ret = drm_vblank_get(dev, crtc);
1184    if (ret) {
1185        DRM_DEBUG("failed to acquire vblank counter, %d\n", ret);
1186        return ret;
1187    }
1188    seq = drm_vblank_count(dev, crtc);
1189
1190    switch (vblwait->request.type & _DRM_VBLANK_TYPES_MASK) {
1191    case _DRM_VBLANK_RELATIVE:
1192        vblwait->request.sequence += seq;
1193        vblwait->request.type &= ~_DRM_VBLANK_RELATIVE;
1194    case _DRM_VBLANK_ABSOLUTE:
1195        break;
1196    default:
1197        ret = -EINVAL;
1198        goto done;
1199    }
1200
1201    if (flags & _DRM_VBLANK_EVENT) {
1202        /* must hold on to the vblank ref until the event fires
1203         * drm_vblank_put will be called asynchronously
1204         */
1205        return drm_queue_vblank_event(dev, crtc, vblwait, file_priv);
1206    }
1207
1208    if ((flags & _DRM_VBLANK_NEXTONMISS) &&
1209        (seq - vblwait->request.sequence) <= (1<<23)) {
1210        vblwait->request.sequence = seq + 1;
1211    }
1212
1213    DRM_DEBUG("waiting on vblank count %d, crtc %d\n",
1214          vblwait->request.sequence, crtc);
1215    dev->last_vblank_wait[crtc] = vblwait->request.sequence;
1216    DRM_WAIT_ON(ret, dev->vbl_queue[crtc], 3 * DRM_HZ,
1217            (((drm_vblank_count(dev, crtc) -
1218               vblwait->request.sequence) <= (1 << 23)) ||
1219             !dev->irq_enabled));
1220
1221    if (ret != -EINTR) {
1222        struct timeval now;
1223
1224        vblwait->reply.sequence = drm_vblank_count_and_time(dev, crtc, &now);
1225        vblwait->reply.tval_sec = now.tv_sec;
1226        vblwait->reply.tval_usec = now.tv_usec;
1227
1228        DRM_DEBUG("returning %d to client\n",
1229              vblwait->reply.sequence);
1230    } else {
1231        DRM_DEBUG("vblank wait interrupted by signal\n");
1232    }
1233
1234done:
1235    drm_vblank_put(dev, crtc);
1236    return ret;
1237}
1238
1239void drm_handle_vblank_events(struct drm_device *dev, int crtc)
1240{
1241    struct drm_pending_vblank_event *e, *t;
1242    struct timeval now;
1243    unsigned long flags;
1244    unsigned int seq;
1245
1246    seq = drm_vblank_count_and_time(dev, crtc, &now);
1247
1248    spin_lock_irqsave(&dev->event_lock, flags);
1249
1250    list_for_each_entry_safe(e, t, &dev->vblank_event_list, base.link) {
1251        if (e->pipe != crtc)
1252            continue;
1253        if ((seq - e->event.sequence) > (1<<23))
1254            continue;
1255
1256        DRM_DEBUG("vblank event on %d, current %d\n",
1257              e->event.sequence, seq);
1258
1259        e->event.sequence = seq;
1260        e->event.tv_sec = now.tv_sec;
1261        e->event.tv_usec = now.tv_usec;
1262        drm_vblank_put(dev, e->pipe);
1263        list_move_tail(&e->base.link, &e->base.file_priv->event_list);
1264        wake_up_interruptible(&e->base.file_priv->event_wait);
1265        trace_drm_vblank_event_delivered(e->base.pid, e->pipe,
1266                         e->event.sequence);
1267    }
1268
1269    spin_unlock_irqrestore(&dev->event_lock, flags);
1270
1271    trace_drm_vblank_event(crtc, seq);
1272}
1273
1274/**
1275 * drm_handle_vblank - handle a vblank event
1276 * @dev: DRM device
1277 * @crtc: where this event occurred
1278 *
1279 * Drivers should call this routine in their vblank interrupt handlers to
1280 * update the vblank counter and send any signals that may be pending.
1281 */
1282bool drm_handle_vblank(struct drm_device *dev, int crtc)
1283{
1284    u32 vblcount;
1285    s64 diff_ns;
1286    struct timeval tvblank;
1287    unsigned long irqflags;
1288
1289    if (!dev->num_crtcs)
1290        return false;
1291
1292    /* Need timestamp lock to prevent concurrent execution with
1293     * vblank enable/disable, as this would cause inconsistent
1294     * or corrupted timestamps and vblank counts.
1295     */
1296    spin_lock_irqsave(&dev->vblank_time_lock, irqflags);
1297
1298    /* Vblank irq handling disabled. Nothing to do. */
1299    if (!dev->vblank_enabled[crtc]) {
1300        spin_unlock_irqrestore(&dev->vblank_time_lock, irqflags);
1301        return false;
1302    }
1303
1304    /* Fetch corresponding timestamp for this vblank interval from
1305     * driver and store it in proper slot of timestamp ringbuffer.
1306     */
1307
1308    /* Get current timestamp and count. */
1309    vblcount = atomic_read(&dev->_vblank_count[crtc]);
1310    drm_get_last_vbltimestamp(dev, crtc, &tvblank, DRM_CALLED_FROM_VBLIRQ);
1311
1312    /* Compute time difference to timestamp of last vblank */
1313    diff_ns = timeval_to_ns(&tvblank) -
1314          timeval_to_ns(&vblanktimestamp(dev, crtc, vblcount));
1315
1316    /* Update vblank timestamp and count if at least
1317     * DRM_REDUNDANT_VBLIRQ_THRESH_NS nanoseconds
1318     * difference between last stored timestamp and current
1319     * timestamp. A smaller difference means basically
1320     * identical timestamps. Happens if this vblank has
1321     * been already processed and this is a redundant call,
1322     * e.g., due to spurious vblank interrupts. We need to
1323     * ignore those for accounting.
1324     */
1325    if (abs64(diff_ns) > DRM_REDUNDANT_VBLIRQ_THRESH_NS) {
1326        /* Store new timestamp in ringbuffer. */
1327        vblanktimestamp(dev, crtc, vblcount + 1) = tvblank;
1328
1329        /* Increment cooked vblank count. This also atomically commits
1330         * the timestamp computed above.
1331         */
1332        smp_mb__before_atomic_inc();
1333        atomic_inc(&dev->_vblank_count[crtc]);
1334        smp_mb__after_atomic_inc();
1335    } else {
1336        DRM_DEBUG("crtc %d: Redundant vblirq ignored. diff_ns = %d\n",
1337              crtc, (int) diff_ns);
1338    }
1339
1340    DRM_WAKEUP(&dev->vbl_queue[crtc]);
1341    drm_handle_vblank_events(dev, crtc);
1342
1343    spin_unlock_irqrestore(&dev->vblank_time_lock, irqflags);
1344    return true;
1345}
1346EXPORT_SYMBOL(drm_handle_vblank);
1347

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