Re: [RFC PATCH v6 6/9] media: tegra: Add Tegra210 Video input driver

Sowjanya Komatineni
2020-04-09T18:28:19Z

On 4/9/20 7:50 AM, Dmitry Osipenko wrote:
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> 09.04.2020 06:38, Sowjanya Komatineni пишет:
> ...
>> Tested with 3 buffers and by checking outstanding buffers in process by
>> VI hw and holding to start capture till one outstanding buffer in
>> process by HW.
>> Also tested with 2 buffers without checking for outstanding buffers.
>>
>> In both cases, I see same %CPU for the kthreads and is < 1%
>>
> I don't see where buffers queue max limit is set to 3 in the code, but
> should be okay if CPU isn't getting hogged. Looking forward to v7.
Sorry, correction I meant to say pre-queued buffers before streaming not
num_buffers.
vb2 queue min_buffers_needed was set to 3 as part of one of the issue
debug in earlier version which actually was irrelevant to that issue and
should have been removed. Will remove min_buffers_needed in v7.

I added checking for outstanding requests by hardware just to be safer
although we may not hit this case of issuing more than 1 outstanding
frame capture to VI hardware as capture_frame() waits till it sees frame
start event through HW syncpt increment before proceeding for memory
write and issuing next frame capture.

So issuing frame captures are synchronized with frame start and frame end.

Will remove min_buffers_needed and also explicit check for outstanding
buffers in v7.