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Subject: Re: [RFC PATCH v6 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 4/6/20 2:15 PM, Sowjanya Komatineni wrote:
>
> On 4/6/20 2:11 PM, Dmitry Osipenko wrote:
>> External email: Use caution opening links or attachments
>>
>>
>> 07.04.2020 00:02, Sowjanya Komatineni =D0=BF=D0=B8=D1=88=D0=B5=D1=82:
>>>>>>>> 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=20
>>>>>>> wakeup it
>>>>>>> continues
>>>>>> The wait_event() won't wait if condition is true.
>>>>> condition is checked when waitqueue is woken up
>>>> https://elixir.bootlin.com/linux/v5.6.2/source/include/linux/wait.h#L4=
62=20
>>>>
>>> process is put to sleep until the condition evaluates to true or signal
>>> is received.
>>>
>>> condition is checked each time the waitqueue head is woken up.
>> This is a wrong assumption in accordance to the code.
>
> when every buffer is available as long as we are in streaming, we=20
> should process it.
>
> So if wake up happens when list has buffer, it will be processed but=20
> at a time we limit processing 2 simultaneous buffer capture starts only.
>
Fixing typo.

I meant when ever buffer is available as long as we are in streaming, we=20
should process it.

So capture thread processes as long as buffers are available from user=20
space limiting 2 simultaneous trigger of captures and thread will be in=20
sleep when capture buffers list is empty or no stop thread is signaled.