Hello,
I posted this to linux-usb-users in February:
>I have tried to run a webcam (ov511 based) on my old Cyrix 486 100 Mhz
>using an Opti OHCI card.
>While all applications like vidcat, camstream and xawtv are working well on
>my pentium, only vidcat works for the 486. How can I get xawtv and camstream
>running for my 486 ? Is it possible to patch the device driver(s) to make
>this apps work ?
After Dmitri's reply, I asked Mark McClelland to give me some hints ( Thanks
for the help!).
I have done some tests with vidcat and discovered another problem:
If you try to read frames from an usb webcam on a 486 based board, it will
block after a several frames.
This is independent from:
-the motherboard: I tried two 486 based motherboards with the same result,
and a Pentium III board which worked fine. BTW, it's possible to read frames
on a 486 board running W*98 (if you get a 486 compatible driver)
-the camera: cpia and ov511 blocked after a few frames
-maybe the kernel. I'm now using kernel 2.4.3, but had this problem since
February. All kernels were compiled for the 486.
-maybe the OHCI board: I used it in the Pentium as well as in the 486 boards
-using read() or ioctl (VCMCAPTURE/VCYNC) - calls
-apm. It was deactivated in the kernel.
What has happened:
After a few frames, the camera device driver doesn't receive any interrupts,
so the interrupt handler of the camera device driver (f.e. ov511) isn't
executed any more.
---snip from Mark last email---
>>The interrupt routine wasn't called while blocking. So I guess an
>>interrupt is lost somewhere in the USB stack :-(.
That's how it looks to me too. The driver seems to be handling the
interrupts as expected, until they stop coming in. The MCAPTURE and SYNC
ioctls seem to be working fine even after the interrupts stopped, so I
don't think the driver is stuck in any unusual state (other than waiting
for interrupts).
---snip
Can someone help me to track this down ? My knowledge about the USB stack is
poor, and it's really more difficult than a camera driver. It would be nice
to get USB webcams work on 486 architecture.
Thanks very much in advance,
Franz
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