[linux-dvb] problems capturing analog and digital at the same time with lifeview trio

rghetta birrachiara at tin.it
Sat Sep 9 07:45:11 CEST 2006

rghetta wrote:
> Hartmut Hackmann wrote:
>> rghetta wrote:
>>> Is detecting an over-4-DMA-channels situation and returning a specific
>>> error (perhaps "bandwidth exceeded" or something like that) a viable
>>> option ?
>>> This way only an illegal combination will be flagged and the
>>> application  could have a chance to inform the user or revert to a
>>> more appropriate format.
>> This can be detected and would be far better than nothing. But this message
>> would go into the kernel log. Afaik, there is no way to get this on a
>> display.
>> Its also dangerous to refuse the streaming. Some applications don't have
>> timouts and will simpy hang if a DMA streaimg doesn't happen...
> Uh, sorry, I wasn't clear. I wasn't thinking about a message, but a real
> error.
> To be more precise, making the VIDIOC_S_FMT/VIDIOC_TRY_FMT ioctl fail
> with a specific error code (if I understood correctly the v4l2 api)

Yesterday I looked at mythtv sources. If the VIDIOC_S_FMT ioctl fails
for any reason, it retries using yuy2. So it seems that making the
driver return an error if someone tries to overload the chip can be an
effective solution, at least for mythtv.
Do you think it can be generally useful ?


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