...of course, without a decoder registered, /dev/video0 doesn't do much
:).
I've spent the better part of the night trying to figure out how to best
write a dummy slave device. I tried taking tvp5146.c and making a dummy
device out of it, but I'm not sure how to best approach it. Stripping
out the I2C and hardcoding the V4L settings isn't difficult, but I'm not
sure what to use in place of i2c_device... do I just make another
platform_device? video_device? Plain old device? I'm not sure what the
appropriate starting place would be. My V4L2 and kernel driver kung fu
is a little weak :).
Thanks again for the advice.
Ryan
________________________________
From: Jadav, Brijesh R [mailto:[email protected]]
Sent: Thursday, March 05, 2009 6:05 AM
To: Ryan Talbot; [email protected]
Subject: RE: VPFE
Hi Ryan,
For the device to be created in /dev, you will need a dummy
slave device. vpfe_probe must be called whether slave is available or
not. If this is not getting called, it means there is some vpfe's name
mismatch between name with which driver is registered as a platform
device and name present in the board specific file in
arch/arm/mach-davinci directory.
Thanks,
Brijesh Jadav
________________________________
From: [email protected]
[mailto:[email protected]] On
Behalf Of Ryan Talbot
Sent: Thursday, March 05, 2009 7:42 AM
To: [email protected]
Subject: VPFE
We've got a custom DM6446-based board which has a DM648 pumping
BT656 video directly into the DM6446's VPFE. We're trying to use V4L to
grab the video frames, but are running into some problems. We're using
2.6.28-rc6 with Murali Karicheri's patches applied, and while the
modules load successfully ("vpfe_capture: init successful"), we still
get the following trying to open /dev/video0:
"Can't open /dev/video0: no such device or address".
It is maybe worth noting that we have to create this device node
everytime we boot using mknod. 'cat /proc/devices' does list '81 0
video4linux', though.
I will admit I don't have a great grasp of how the V4L
architecture is supposed to work. We don't have any other hardware
involved other than the DaVinci VPFE, i.e. no decoder chips (they're all
upstream and handled by the DM648). I noticed vpfe_probe never gets
called when modprobing... seems like it should be. Do we need to create
some kind of dummy slave device to get things kicking?
Our board supplier gave us a C64P image that passes video
through from VPFE to VPBE, so the hardware itself is OK. I didn't think
the C64P even had direct access to the VPFE - I thought it relied on the
ARM/DSPLink for video frames - but I guess that shows the depths of my
ignorance.
Any pointers much appreciated, and a big thanks to Murali
Karicheri for his hard work on the patches.
Ryan Talbot
VTTI
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