aboutsummaryrefslogtreecommitdiff
path: root/Documentation/media/v4l-drivers/cafe_ccic.rst
diff options
context:
space:
mode:
authorMauro Carvalho Chehab2016-07-27 10:45:04 -0300
committerMauro Carvalho Chehab2016-07-27 10:45:04 -0300
commit85538b1ad145c67198cb55d02de14ba269cc323d (patch)
tree409fca93b357839b8c89b7099f2888c087694b64 /Documentation/media/v4l-drivers/cafe_ccic.rst
parent9c1958fc326a0a0a533ec8e86ea6fa30977207de (diff)
parentd271d3d9b333c94cd54a12fa506e17772a04617c (diff)
Merge branch 'topic/docs-next' into v4l_for_linus
* topic/docs-next: (322 commits) [media] cx23885-cardlist.rst: add a new card [media] doc-rst: add some needed escape codes [media] doc-rst: kapi: use :c:func: instead of :cpp:func doc-rst: kernel-doc: fix a change introduced by mistake [media] v4l2-ioctl.h add debug info for struct v4l2_ioctl_ops [media] dvb_ringbuffer.h: some documentation improvements [media] v4l2-ctrls.h: fully document the header file [media] doc-rst: Fix some typedef ugly warnings [media] doc-rst: reorganize the kAPI v4l2 chapters [media] rename v4l2-framework.rst to v4l2-intro.rst [media] move V4L2 clocks to a separate .rst file [media] v4l2-fh.rst: add cross references and markups [media] v4l2-fh.rst: add fh contents from v4l2-framework.rst [media] v4l2-fh.h: add documentation for it [media] v4l2-event.rst: add cross-references and markups [media] v4l2-event.h: document all functions [media] v4l2-event.rst: add text from v4l2-framework.rst [media] v4l2-framework.rst: remove videobuf quick chapter [media] v4l2-dev: add cross-references and improve markup [media] doc-rst: move v4l2-dev doc to a separate file ...
Diffstat (limited to 'Documentation/media/v4l-drivers/cafe_ccic.rst')
-rw-r--r--Documentation/media/v4l-drivers/cafe_ccic.rst60
1 files changed, 60 insertions, 0 deletions
diff --git a/Documentation/media/v4l-drivers/cafe_ccic.rst b/Documentation/media/v4l-drivers/cafe_ccic.rst
new file mode 100644
index 000000000000..b98eb3b7cb4a
--- /dev/null
+++ b/Documentation/media/v4l-drivers/cafe_ccic.rst
@@ -0,0 +1,60 @@
+The cafe_ccic driver
+====================
+
+Author: Jonathan Corbet <corbet@lwn.net>
+
+Introdution
+-----------
+
+"cafe_ccic" is a driver for the Marvell 88ALP01 "cafe" CMOS camera
+controller. This is the controller found in first-generation OLPC systems,
+and this driver was written with support from the OLPC project.
+
+Current status: the core driver works. It can generate data in YUV422,
+RGB565, and RGB444 formats. (Anybody looking at the code will see RGB32 as
+well, but that is a debugging aid which will be removed shortly). VGA and
+QVGA modes work; CIF is there but the colors remain funky. Only the OV7670
+sensor is known to work with this controller at this time.
+
+To try it out: either of these commands will work:
+
+.. code-block:: none
+
+ $ mplayer tv:// -tv driver=v4l2:width=640:height=480 -nosound
+ $ mplayer tv:// -tv driver=v4l2:width=640:height=480:outfmt=bgr16 -nosound
+
+The "xawtv" utility also works; gqcam does not, for unknown reasons.
+
+Load time options
+-----------------
+
+There are a few load-time options, most of which can be changed after
+loading via sysfs as well:
+
+ - alloc_bufs_at_load: Normally, the driver will not allocate any DMA
+ buffers until the time comes to transfer data. If this option is set,
+ then worst-case-sized buffers will be allocated at module load time.
+ This option nails down the memory for the life of the module, but
+ perhaps decreases the chances of an allocation failure later on.
+
+ - dma_buf_size: The size of DMA buffers to allocate. Note that this
+ option is only consulted for load-time allocation; when buffers are
+ allocated at run time, they will be sized appropriately for the current
+ camera settings.
+
+ - n_dma_bufs: The controller can cycle through either two or three DMA
+ buffers. Normally, the driver tries to use three buffers; on faster
+ systems, however, it will work well with only two.
+
+ - min_buffers: The minimum number of streaming I/O buffers that the driver
+ will consent to work with. Default is one, but, on slower systems,
+ better behavior with mplayer can be achieved by setting to a higher
+ value (like six).
+
+ - max_buffers: The maximum number of streaming I/O buffers; default is
+ ten. That number was carefully picked out of a hat and should not be
+ assumed to actually mean much of anything.
+
+ - flip: If this boolean parameter is set, the sensor will be instructed to
+ invert the video image. Whether it makes sense is determined by how
+ your particular camera is mounted.