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Subject: Re: [RFC PATCH v9 6/9] media: tegra: Add Tegra210 Video input driver
From:   Sowjanya Komatineni <skomatineni@nvidia.com>
To:     Dmitry Osipenko <digetx@gmail.com>, <thierry.reding@gmail.com>,
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On 4/23/20 4:19 PM, Sowjanya Komatineni wrote:
>
> On 4/23/20 4:16 PM, Dmitry Osipenko wrote:
>> External email: Use caution opening links or attachments
>>
>>
>> 22.04.2020 09:18, Sowjanya Komatineni =D0=BF=D0=B8=D1=88=D0=B5=D1=82:
>>> +static int chan_capture_kthread_start(void *data)
>>> +{
>>> +=C2=A0=C2=A0=C2=A0=C2=A0 struct tegra_vi_channel *chan =3D data;
>>> +=C2=A0=C2=A0=C2=A0=C2=A0 struct tegra_channel_buffer *buf;
>>> +=C2=A0=C2=A0=C2=A0=C2=A0 int err =3D 0;
>>> +
>>> +=C2=A0=C2=A0=C2=A0=C2=A0 set_freezable();
>>> +
>>> +=C2=A0=C2=A0=C2=A0=C2=A0 while (1) {
>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0 try_to_freeze();
>>> +
>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0 wait_event_interruptible(chan->start_wait,
>>> + !list_empty(&chan->capture) ||
>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0 kthread_should_stop());
>>> +
>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0 if (kthread_should_stop())
>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 break;
>>> +
>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0 /*
>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0 * Source is not streaming if error is non-zero.
>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0 * So, do not dequeue buffers on capture error.
>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0 */
>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0 if (err)
>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 continue;
>> This will result in an endless loop, I suppose it wasn't the intention.
>
> no it will not. on error we report vb2_queue_error which will do=20
> streaming stop request.
>
> So thread will be stopped on streaming stop request thru kthread stop=20
> signal
To be clear on error it reports vb2 queue error and waits for stop=20
streaming to happen