2016-09-12 21:57 GMT+03:00 Bin Liu <b-liu@xxxxxx>:
> Hi,
>
> On Mon, Sep 12, 2016 at 11:52:46AM +0300, Matwey V. Kornilov wrote:
>> 2016-09-12 6:28 GMT+03:00 Bin Liu <b-liu@xxxxxx>:
>> > Hi,
>> >
>> > On Tue, Aug 30, 2016 at 11:44:33PM +0300, Matwey V. Kornilov wrote:
>> >> 2016-08-30 21:30 GMT+03:00 Bin Liu <b-liu@xxxxxx>:
>> >> > Hi,
>> >> >
>> >> > On Sun, Aug 28, 2016 at 01:13:55PM +0300, Matwey V. Kornilov wrote:
>> >> >> Hello Bin,
>> >> >>
>> >> >> I would like to start new thread on my issue. Let me recall where the issue is:
>> >> >> There is 100% frame lost in pwc webcam driver due to lots of
>> >> >> zero-length packages coming from musb driver.
>> >> >
>> >> > What is the video resolution and fps?
>> >>
>> >> 640x480 YUV420 10 frames per second.
>> >> pwc uses proprietary compression during device-host transmission, but
>> >> I don't know how effective it is.
>> >
>> > The data rate for VGA YUV420 @10fps is 640x480*1.5*10 = 4.6MB/s, which
>> > is much higher than full-speed 12Mbps. So the video data on the bus is
>> > compressed, not YUV420, I believe.
>> >
>> >>
>> >> >
>> >> >> The issue is present in all kernels (including 4.8) starting from the commit:
>> >> >>
>> >> >> f551e13529833e052f75ec628a8af7b034af20f9 ("Revert "usb: musb:
>> >> >> musb_host: Enable HCD_BH flag to handle urb return in bottom half"")
>> >> >
>> >> > What is the behavior without this commit?
>> >>
>> >> Without this commit all frames are being received correctly. Single
>> >
>> > Which means without this commit your camera has been working without
>> > issues, and this is a regression with this commit, right?
>> >
>>
>> Right
>
> Okay, thanks for confirming.
>
> But we cannot just simply add this flag, as it breaks many other use
> cases. I will continue work on this to find a solution which works on
> all use cases.
>
Ok, thank you.
> Regards,
> -Bin.
>
--
With best regards,
Matwey V. Kornilov.
Sternberg Astronomical Institute, Lomonosov Moscow State University, Russia
119991, Moscow, Universitetsky pr-k 13, +7 (495) 9392382
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