From: Bin Liu <b-liu@ti.com>
To: "Matwey V. Kornilov" <matwey@sai.msu.ru>
Cc: Alan Stern <stern@rowland.harvard.edu>, <hdegoede@redhat.com>,
<linux-media@vger.kernel.org>, <linux-usb@vger.kernel.org>
Subject: Re: musb: isoc pkt loss with pwc
Date: Mon, 12 Sep 2016 13:57:09 -0500 [thread overview]
Message-ID: <20160912185709.GL18340@uda0271908> (raw)
In-Reply-To: <CAJs94EbNjkjN4eMY03eH3o=xVe+CGB95GQ+a5PsmsNUrDzi8mQ@mail.gmail.com>
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@ti.com>:
> > 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@ti.com>:
> >> > 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.
Regards,
-Bin.
next prev parent reply other threads:[~2016-09-12 18:57 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-28 10:13 musb: isoc pkt loss with pwc Matwey V. Kornilov
2016-08-30 18:30 ` Bin Liu
2016-08-30 20:44 ` Matwey V. Kornilov
2016-09-12 3:28 ` Bin Liu
2016-09-12 8:52 ` Matwey V. Kornilov
2016-09-12 18:57 ` Bin Liu [this message]
2016-09-12 19:38 ` Matwey V. Kornilov
2016-10-15 19:25 ` Matwey V. Kornilov
2016-11-01 20:33 ` Bin Liu
2017-01-27 17:13 ` Matwey V. Kornilov
2017-04-15 14:58 ` Matwey V. Kornilov
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