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Date: Fri, 10 Apr 2020 21:47:50 +0300 From: Dmitry Osipenko <digetx@...il.com> To: Sowjanya Komatineni <skomatineni@...dia.com>, thierry.reding@...il.com, jonathanh@...dia.com, frankc@...dia.com, hverkuil@...all.nl, sakari.ailus@....fi, helen.koike@...labora.com Cc: sboyd@...nel.org, linux-media@...r.kernel.org, devicetree@...r.kernel.org, linux-clk@...r.kernel.org, linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [RFC PATCH v6 6/9] media: tegra: Add Tegra210 Video input driver 09.04.2020 21:28, Sowjanya Komatineni пишет: > > On 4/9/20 7:50 AM, Dmitry Osipenko wrote: >> External email: Use caution opening links or attachments >> >> >> 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. It's still not clear to me how the "pre-queued buffers" will be limited. I'll take another look at the v7.
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