Hi,
On 06/07/2011 07:24 AM, John McMaster wrote:
On 06/06/2011 12:43 AM, Hans de Goede wrote:
Hi,
On 06/06/2011 07:40 AM, John McMaster wrote:
On 06/03/2011 06:22 AM, Hans de Goede wrote:
Hi,
On 06/03/2011 02:15 PM, Mauro Carvalho Chehab wrote:
Em 03-06-2011 02:40, John McMaster escreveu:
I'd like to write a driver for an Anchor Chips (seems to be bought by
Cypress) USB camera Linux driver sold as an AmScope MD1800. It seems
like this implies I need to write a V4L2 driver. The camera does not
seem its currently supported (checked on Fedora 13 / 2.6.34.8) and I
did
not find any information on it in mailing list archives. Does anyone
know or can help me identify if a similar camera might already be
supported?
I've no idea. Better to wait for a couple days for developers to
manifest
about that, if they're already working on it.
lsusb gives the following output:
Bus 001 Device 111: ID 0547:4d88 Anchor Chips, Inc.
I've started reading the "Video for Linux Two API Specification"
which
seems like a good starting point and will move onto using source
code as
appropriate. Any help would be appreciated. Thanks!
You'll find other useful information at linuxtv.org wiki page. The
better
is to write it as a sub-driver for gspca. The gspca core have already
all
that it is needed for cameras. So, you'll need to focus only at the
device-specific
stuff.
I can second that you should definitely use gspca for usb webcam(ish)
device
drivers. As for how to go about this, first of all grep through the
windows drivers
for strings which may hint on the actual bridge chip used, chances are
good
there is an already supported bridge inside the camera.
If not then make usb dumps, and start reverse engineering ...
Usually it is enough to replay the windows init sequence to get the
device
to stream over either an bulk or iso endpoint, and then it is time to
figure out what that stream contains (jpeg, raw bayer, some custom
format ???)
Regards,
Hans
Thanks for the response. I replayed some packets (using libusb) and am
able to get something resembling the desired image through its bulk
endpoint. So now I just need to figure out how to decode it better,
options, etc. I'll post back to the list once I get something
moderately stable running and have taken a swing at the kernel driver.
Hmm, bulk you say and cypress and 8mp usb2.0 have you tried looking
at the gspca-ovfx2 driver? Likely you've an ovfx2 cam with an as of
yet unknown usb-id. Chances are just adding the id is enough, although
your sensor may be unknown.
Regards,
Hans
If it helps, I should have also mentioned that with a small amount of
digging I found that the camera unit is put together by ScopeTek. My
reference WIP implementation is at
https://github.com/JohnDMcMaster/uvscopetek which I'm comparing to
2.6.39.1 drivers.
Anyway, looking at reg_w() I see that it likes to make 0x00, 0x02, or
0x0A requests where as mine makes 0x01, 0x0A, and mostly 0x0B requests.
I do see that it tends to want a byte back though like mine (0x0A except
at end). My code has a few 3 byte returns (byte 0 varies, byte 1 fixed
at 0x00, byte 2 fixed at 0x08 like others), so I'm not sure if its a
good match for reg read. Following that I tried to grep around some
more for a number of the more interesting numbers (eg: 90D8 as opposed
to 0001) in the $SRC/drivers/media/video dir and could only find
scattered matches. I do realize that a lot of the more esoteric numbers
could be specific settings and not registers, commands, etc. Or maybe
tofx2 is related and I'm not understanding the bridge concept?
I think you may have been looking at the wrong driver, if your trace shows
mostly 0x0a, 0x0b and 0x02 requests then chances are high it is indeed
an ovfx2, the ovfx2 driver is part of drivers/media/video/gspca/ov519.c
because it shares a bunch of functions (mostly sensor detect stuff) with
the ov511/ov518/ov519 driver.
And it makes 0x0a request for ovfx2 (bridge) register writes, 0x0b
requests for ovfx2 (bridge) register reads and 0x02 requests for i2c
writes.
If things indeed seem a better match with the ovfx2 support in ov519.c,
one quick way to find out if it is an ovfx2 is to just add the usb-id of
your camera to ov519.c as an ovfx2 camera, and load the driver, first
thing the driver does is try to detect the sensor type through the i2c
bus between the bridge and the sensor, if that works (even if it
detects an unknown sensor, but the sensor id found seems sensible) it
it likely is an ovfx2.
You could also try grapping for strings like fx2 and cypress in the windows
driver. Also try looking at the .inf file from the windows driver, if that
contains different (maybe commented out) usb-ids of potentially compatible
cams.
Regards,
Hans
John
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