Hi All,
I'm a Linux enthusiast / developer. Lately I'm mainly active doing development
for Fedora and writing kernel drivers (and as my day job I'm a lecturer in
Computer Science).
Fedora has a policy of not shipping a heavily patched kernel, but instead tries
to work with upstream to get any needed patches integrated. This policy extends
to not shipping any addon drivers, but rather working to get drivers integrated
upstream.
As such I've decided to start spending my spare time on getting more and better
usb webcam support integrated upstream (for non usb video class devices). I
wanted to have something to show, so I've gone to the store, bought a couple of
webcams and started hacking and learning.
2 days ago I have finished my first pretty clean, standalone v4l2 webcam driver
for Pixart pac207 webcams.
In the beginning I modelled this driver after the zc301 and sn9c102 driver
which are currently already in the mainline kernel, using the memory management
and other structure from these drivers and filling in the hardware dependent
parts with the pac207 code from the out of tree gpsca driver.
During the development I kept the buffer management from the zc301 driver, but
modelled the rest of the driver more and more after gspca. For example don't
start the iso stream on device open and throw away iso packets received before
the stream-on ioctl, but instead start and stop the stream as needed.
This has resulted in what I consider a nice and clean pac207 driver. But when I
finished it I noticed that a lot of code in their was generic code for any
simple usb webcam.
Since I plan to write standalone v4l2 drivers for mainline inclusion for other
simple usb webcams I spend the last 2 days splitting the code of my pac207
driver into a generic usbvideo2 core (the kernel already has usbvideo, which
has a number of v4l1 drivers) and a camera specific pac207 driver which builds
on top of the usbvideo2 core.
So I've ended up with a model very much like gspca, but then not one large
monolithic kernel module, but a more modular design with an core kernel module
with (hopefully) generic code for simple usb webcam's, and a per usb controller
chip type specific module (currently only one for pac207 controllers), and
ofcourse very important this is code for v4l2 drivers, whereas the current
gspca is v4l1.
I just recently (today) learned that there is work underway to make a v4l2
version of gspca by Jean-François Moine: http://moinejf.free.fr/ ), I hope that
we can work together somehow on getting support for all the webcam's supported
in gscpa integrated into the mainline kernel with a v4l2 interface.
I'll be sending 2 seperate mails one with my standalone pac207 driver, and one
with the usbvideo2 core and a pac207 driver using this core, I'll include
Makefiles for out of tree building with both of them so that interested people
can test them.
I'm currently posting these as .c files for easy reading and compilation /
testing, but I still hope to get a lot of feedback / a thorough review, esp of
the core <-> pac207 split version as I hope to submit that as a patch for
mainline inclusion soon.
Thanks & Regards,
Hans
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