From: Sowjanya Komatineni <skomatineni@nvidia.com>
To: Dmitry Osipenko <digetx@gmail.com>, <thierry.reding@gmail.com>,
<jonathanh@nvidia.com>, <frankc@nvidia.com>, <hverkuil@xs4all.nl>,
<sakari.ailus@iki.fi>, <helen.koike@collabora.com>
Cc: <sboyd@kernel.org>, <linux-media@vger.kernel.org>,
<devicetree@vger.kernel.org>, <linux-clk@vger.kernel.org>,
<linux-tegra@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH v6 6/9] media: tegra: Add Tegra210 Video input driver
Date: Wed, 8 Apr 2020 12:38:21 -0700 [thread overview]
Message-ID: <ced73258-6f4b-e970-4ca5-ecdf1808a4c3@nvidia.com> (raw)
In-Reply-To: <a638bb8e-bb50-7aa5-05a0-8de1c6207ba7@nvidia.com>
On 4/8/20 11:58 AM, Sowjanya Komatineni wrote:
>
> On 4/8/20 10:45 AM, Sowjanya Komatineni wrote:
>>
>> On 4/8/20 7:21 AM, Dmitry Osipenko wrote:
>>> External email: Use caution opening links or attachments
>>>
>>>
>>> 08.04.2020 03:00, Sowjanya Komatineni пишет:
>>> ...
>>>>>>>> I suppose that taking a shot takes at least few milliseconds,
>>>>>>>> which
>>>>>>>> should be unacceptable to waste.
>>>>>>> As long as buffers are in queue we have to keep processing each
>>>>>>> buffer and between buffers obviously we have to wait for previous
>>>>>>> frames to finish and this why we have separate thread for frame
>>>>>>> finish where we can have next buffer capture ready and issue while
>>>>>>> previous frame memory write happens
>>>>> Also we specified numbers buffers as 3 to vb2 queue. So this is rare
>>>>> case but to prevent issuing more than 2 at a time as VI HW is only
>>>>> double buffered and syncpt fifo max depth is 2 added this to be
>>>>> safer.
>>>> To be more clear, when more buffers are enqueued from userspace always
>>>> capture list will be full and thread will be busy in capture till
>>>> either
>>>> error or stop stream request happens.
>>>>
>>> If kthreads take more than 1% of CPU time during capture (video) with
>>> more than 2 buffers in queue, then it's not good and I think you should
>>> do something about it. If kthreads stay at ~0%, then it should be okay
>>> as-is.
>>
>> VI outstanding requests max can only be 2 as syncpt fifo depth is 2
>> and waiting to issue next capture when already 2 captures are
>> inflight happens only during beginning of streaming where buffers
>> allocated go thru capture for first time after queuing.
>>
>> same buffers are returned to userspace after capture and same
>> allocated buffers will be queued back for subsequent captures.
>>
>> So this case of holding to issue single shot when already single shot
>> is issue for 2 frames simultaneous happens only during beginning of
>> start stream and also we set num_buffers to allocate for queue as 3
>> although 2 is good enough where we will not hit this case even during
>> streaming start with 2 buffers
>>
> As 2 buffers are good enough to be clear will update in v7 to use 2
> buffers so we don't need to check for more than 2 outstanding buffers.
correction: With 3 buffers, as soon as buffer is available capture
starts. So right most times I see it waiting for few ms before 3rd
capture to get through.
As only 2 frames single shot can be issued in sequence (inflight
requests), instead of waiting for 1 of the request to finish, we can use
2 buffers and avoid waiting as 2 buffers are good enough. Will change
this in v7.
next prev parent reply other threads:[~2020-04-08 19:38 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-04 1:24 [RFC PATCH v6 0/9] Add Tegra driver for video capture Sowjanya Komatineni
2020-04-04 1:24 ` [RFC PATCH v6 1/9] arm64: tegra: Fix sor powergate clocks and reset Sowjanya Komatineni
2020-04-04 1:25 ` [RFC PATCH v6 2/9] arm64: tegra: Add reset-cells to mc Sowjanya Komatineni
2020-04-04 1:25 ` [RFC PATCH v6 3/9] dt-bindings: clock: tegra: Add clk id for CSI TPG clock Sowjanya Komatineni
2020-04-14 18:12 ` Rob Herring
2020-04-04 1:25 ` [RFC PATCH v6 4/9] clk: tegra: Add Tegra210 CSI TPG clock gate Sowjanya Komatineni
2020-04-04 1:25 ` [RFC PATCH v6 5/9] dt-binding: tegra: Add VI and CSI bindings Sowjanya Komatineni
2020-04-14 18:14 ` Rob Herring
2020-04-04 1:25 ` [RFC PATCH v6 6/9] media: tegra: Add Tegra210 Video input driver Sowjanya Komatineni
2020-04-05 19:37 ` Dmitry Osipenko
2020-04-06 18:58 ` Sowjanya Komatineni
2020-04-05 19:45 ` Dmitry Osipenko
2020-04-05 19:57 ` Dmitry Osipenko
2020-04-05 19:51 ` Dmitry Osipenko
2020-04-05 20:35 ` Dmitry Osipenko
2020-04-06 15:35 ` Sowjanya Komatineni
2020-04-06 16:05 ` Dmitry Osipenko
2020-04-06 16:12 ` Sowjanya Komatineni
2020-04-06 16:29 ` Dmitry Osipenko
2020-04-06 16:37 ` Sowjanya Komatineni
2020-04-06 17:02 ` Sowjanya Komatineni
2020-04-06 19:53 ` Dmitry Osipenko
2020-04-06 20:05 ` Sowjanya Komatineni
2020-04-06 20:28 ` Dmitry Osipenko
2020-04-06 20:30 ` Sowjanya Komatineni
2020-04-05 20:54 ` Dmitry Osipenko
2020-04-05 21:11 ` Dmitry Osipenko
2020-04-06 15:41 ` Sowjanya Komatineni
2020-04-06 16:11 ` Dmitry Osipenko
2020-04-07 19:05 ` Sowjanya Komatineni
2020-04-06 19:48 ` Dmitry Osipenko
2020-04-06 20:00 ` Sowjanya Komatineni
2020-04-06 20:02 ` Dmitry Osipenko
2020-04-06 20:20 ` Sowjanya Komatineni
2020-04-06 20:37 ` Dmitry Osipenko
2020-04-06 20:38 ` Sowjanya Komatineni
2020-04-06 20:43 ` Sowjanya Komatineni
2020-04-06 20:54 ` Dmitry Osipenko
2020-04-06 21:18 ` Sowjanya Komatineni
2020-04-06 20:45 ` Dmitry Osipenko
2020-04-06 20:50 ` Sowjanya Komatineni
2020-04-06 20:53 ` Dmitry Osipenko
2020-04-06 20:55 ` Sowjanya Komatineni
2020-04-06 20:56 ` Dmitry Osipenko
2020-04-06 21:02 ` Sowjanya Komatineni
2020-04-06 21:11 ` Dmitry Osipenko
2020-04-06 21:15 ` Sowjanya Komatineni
2020-04-06 21:39 ` Sowjanya Komatineni
2020-04-06 22:00 ` Sowjanya Komatineni
2020-04-06 22:07 ` Sowjanya Komatineni
2020-04-06 23:18 ` Dmitry Osipenko
2020-04-06 23:48 ` Sowjanya Komatineni
2020-04-06 23:50 ` Sowjanya Komatineni
2020-04-07 21:08 ` Sowjanya Komatineni
2020-04-07 22:08 ` Dmitry Osipenko
2020-04-07 22:14 ` Dmitry Osipenko
2020-04-07 22:22 ` Sowjanya Komatineni
2020-04-07 23:12 ` Dmitry Osipenko
[not found] ` <1a31cd60-739f-0660-1c45-31487d2f2128@nvidia.com>
2020-04-07 23:38 ` Sowjanya Komatineni
2020-04-07 23:56 ` Sowjanya Komatineni
2020-04-07 23:57 ` Sowjanya Komatineni
2020-04-07 23:59 ` Sowjanya Komatineni
2020-04-08 0:00 ` Sowjanya Komatineni
2020-04-08 14:21 ` Dmitry Osipenko
2020-04-08 17:45 ` Sowjanya Komatineni
2020-04-08 18:58 ` Sowjanya Komatineni
2020-04-08 19:38 ` Sowjanya Komatineni [this message]
2020-04-09 3:38 ` Sowjanya Komatineni
2020-04-09 14:50 ` Dmitry Osipenko
2020-04-09 18:28 ` Sowjanya Komatineni
2020-04-10 18:47 ` Dmitry Osipenko
2020-04-10 18:59 ` Sowjanya Komatineni
2020-04-10 19:45 ` Dmitry Osipenko
2020-04-07 19:39 ` Dmitry Osipenko
2020-04-07 19:42 ` Sowjanya Komatineni
2020-04-10 19:47 ` Dmitry Osipenko
2020-04-04 1:25 ` [RFC PATCH v6 7/9] MAINTAINERS: Add Tegra Video driver section Sowjanya Komatineni
2020-04-04 1:25 ` [RFC PATCH v6 8/9] dt-bindings: reset: Add ID for Tegra210 VI reset Sowjanya Komatineni
2020-04-14 18:14 ` Rob Herring
2020-04-04 1:25 ` [RFC PATCH v6 9/9] arm64: tegra: Add Tegra VI CSI support in device tree Sowjanya Komatineni
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