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: Tue, 7 Apr 2020 16:59:05 -0700 [thread overview]
Message-ID: <7895b9c6-f27d-8939-73d7-67d785e1a8b7@nvidia.com> (raw)
In-Reply-To: <603084a5-249a-4fe2-3646-e9335ef9ab43@nvidia.com>
On 4/7/20 4:38 PM, Sowjanya Komatineni wrote:
>
> On 4/7/20 4:36 PM, Sowjanya Komatineni wrote:
>>
>> On 4/7/20 4:12 PM, Dmitry Osipenko wrote:
>>> External email: Use caution opening links or attachments
>>>
>>>
>>> 08.04.2020 01:22, Sowjanya Komatineni пишет:
>>>> On 4/7/20 3:08 PM, Dmitry Osipenko wrote:
>>>>> External email: Use caution opening links or attachments
>>>>>
>>>>>
>>>>> 08.04.2020 00:08, Sowjanya Komatineni пишет:
>>>>> ...
>>>>>>>> I think you need a semaphore with resource count = 2.
>>>>>>> we hold on to issuing capture if more than 2 buffers are queued
>>>>>>> and it
>>>>>>> continues only after fifo has min 1 slot empty
>>>>>> Just want to close on this part of feedback. Hope above
>>>>>> explanation is
>>>>>> clear regarding triggering/issuing at max 2 frame capture to VI
>>>>>> HW and
>>>>>> also regarding capture threads where they use
>>>>>> wait_event_interruptible
>>>>>> to prevent blocking waiting for buffers to be available for
>>>>>> captures.
>>>>>>
>>>>>> So no changes related to this part are needed in v7.
>>>>> From what I see in the code, you "hold on" by making kthread to
>>>>> spin in
>>>>> a busy-loop while caps_inflight >= SYNCPT_FIFO_DEPTH. So some change
>>>>> should be needed to prevent this.
>>>>>
>>>>> The wait_event_interruptible seems should be okay.
>>>> We don't want to prevent that as we already have buffers available for
>>>> capture so as soon as VI HW issuing single shot is done and when min 1
>>>> slot is empty we should continue with issuing for another capture.
>>>>
>>>> As long as buffers are available, we should continue to capture and
>>>> should not hold
>>>>
>>> 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.
next prev parent reply other threads:[~2020-04-07 23:59 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 [this message]
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
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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