Re: [Spca50x-devs] Self Introduction: Hans de Goede
- Date: Fri, 28 Mar 2008 23:33:52 +0100
- From: Thomas Kaiser <spca5xx@xxxxxxxxxxxxxxx>
- Subject: Re: [Spca50x-devs] Self Introduction: Hans de Goede
Hans de Goede wrote:
> 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).
Me to :-)
> 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
> 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.
As far as I know, heavy data processing like decoding jpeg or decoding the
compression format of PAC207 is not allowed in kernel space. So, I am not sure
if you can get this upstream?
> 2 days ago I have finished my first pretty clean, standalone v4l2 webcam driver
> for Pixart pac207 webcams.
Nice to see :-). It is on my todo list. Now, I can skip it ;-)
> 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.
It looks like you both a working on the same thing, separated. I think yours and
Jean-François idea is the right way to go (thumps up). Work together.
> 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.
As soon as I have time I will start to test.
Some weekends ago, I was trying to test Jean-François driver but I got a lot of
difficult because of my setup and finally faulty hardware :-( I am still working
on recover my faulty hardware.....
> Thanks & Regards,
PS: I initial started the PAC207 support for gspca. If you have any specific
question about PAC207, don't hesitate to contact me.
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