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Subject: Re: [RFC PATCH v6 6/9] media: tegra: Add Tegra210 Video input driver
To:     Dmitry Osipenko <digetx@gmail.com>, <thierry.reding@gmail.com>,
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References: <1585963507-12610-1-git-send-email-skomatineni@nvidia.com>
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From:   Sowjanya Komatineni <skomatineni@nvidia.com>
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Date:   Mon, 6 Apr 2020 13:50:35 -0700
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On 4/6/20 1:45 PM, Dmitry Osipenko wrote:
> External email: Use caution opening links or attachments
>
>
> 04.04.2020 04:25, Sowjanya Komatineni =D0=BF=D0=B8=D1=88=D0=B5=D1=82:
>> +static int chan_capture_kthread_start(void *data)
>> +{
>> +     struct tegra_vi_channel *chan =3D data;
>> +     struct tegra_channel_buffer *buf;
>> +     int err =3D 0;
>> +     int caps_inflight;
>> +
>> +     set_freezable();
>> +
>> +     while (1) {
>> +             try_to_freeze();
>> +
>> +             wait_event_interruptible(chan->start_wait,
>> +                                      !list_empty(&chan->capture) ||
>> +                                      kthread_should_stop());
>> +             /*
>> +              * Frame start and MW_ACK_DONE syncpoint condition FIFOs a=
re
>> +              * of max depth 2. So make sure max 2 capture requests are
>> +              * in process by the hardware at a time.
>> +              */
>> +             while (!(kthread_should_stop() || list_empty(&chan->captur=
e))) {
>> +                     caps_inflight =3D chan->capture_reqs - chan->seque=
nce;
>> +                     /*
>> +                      * Source is not streaming if error is non-zero.
>> +                      * So, do not dequeue buffers on capture error or =
when
>> +                      * syncpoint requests in FIFO are full.
>> +                      */
>> +                     if (err || caps_inflight >=3D SYNCPT_FIFO_DEPTH)
>> +                             break;
> Am I understanding correctly that this thread will take 100% CPU,
> spinning here, if more than 2 frame-captures queued?
on more than 2 frames captures, it breaks thread and on next wakeup it=20
continues