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1 | "cafe_ccic" is a driver for the Marvell 88ALP01 "cafe" CMOS camera |
2 | controller. This is the controller found in first-generation OLPC systems, |
3 | and this driver was written with support from the OLPC project. |
4 | |
5 | Current status: the core driver works. It can generate data in YUV422, |
6 | RGB565, and RGB444 formats. (Anybody looking at the code will see RGB32 as |
7 | well, but that is a debugging aid which will be removed shortly). VGA and |
8 | QVGA modes work; CIF is there but the colors remain funky. Only the OV7670 |
9 | sensor is known to work with this controller at this time. |
10 | |
11 | To try it out: either of these commands will work: |
12 | |
13 | mplayer tv:// -tv driver=v4l2:width=640:height=480 -nosound |
14 | mplayer tv:// -tv driver=v4l2:width=640:height=480:outfmt=bgr16 -nosound |
15 | |
16 | The "xawtv" utility also works; gqcam does not, for unknown reasons. |
17 | |
18 | There are a few load-time options, most of which can be changed after |
19 | loading via sysfs as well: |
20 | |
21 | - alloc_bufs_at_load: Normally, the driver will not allocate any DMA |
22 | buffers until the time comes to transfer data. If this option is set, |
23 | then worst-case-sized buffers will be allocated at module load time. |
24 | This option nails down the memory for the life of the module, but |
25 | perhaps decreases the chances of an allocation failure later on. |
26 | |
27 | - dma_buf_size: The size of DMA buffers to allocate. Note that this |
28 | option is only consulted for load-time allocation; when buffers are |
29 | allocated at run time, they will be sized appropriately for the current |
30 | camera settings. |
31 | |
32 | - n_dma_bufs: The controller can cycle through either two or three DMA |
33 | buffers. Normally, the driver tries to use three buffers; on faster |
34 | systems, however, it will work well with only two. |
35 | |
36 | - min_buffers: The minimum number of streaming I/O buffers that the driver |
37 | will consent to work with. Default is one, but, on slower systems, |
38 | better behavior with mplayer can be achieved by setting to a higher |
39 | value (like six). |
40 | |
41 | - max_buffers: The maximum number of streaming I/O buffers; default is |
42 | ten. That number was carefully picked out of a hat and should not be |
43 | assumed to actually mean much of anything. |
44 | |
45 | - flip: If this boolean parameter is set, the sensor will be instructed to |
46 | invert the video image. Whether it makes sense is determined by how |
47 | your particular camera is mounted. |
48 | |
49 | Work is ongoing with this driver, stay tuned. |
50 | |
51 | jon |
52 | |
53 | Jonathan Corbet |
54 | corbet@lwn.net |
55 |
Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master
Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9