From: Dmitry Osipenko <digetx@gmail.com>
To: Sowjanya Komatineni <skomatineni@nvidia.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: Mon, 6 Apr 2020 22:53:51 +0300 [thread overview]
Message-ID: <abe82fd1-0464-0627-6c97-39c896e53dd0@gmail.com> (raw)
In-Reply-To: <9038ce90-ac53-93e7-ce65-57f6ff1e9b30@nvidia.com>
06.04.2020 20:02, Sowjanya Komatineni пишет:
>
> On 4/6/20 9:37 AM, Sowjanya Komatineni wrote:
>>
>> On 4/6/20 9:29 AM, Dmitry Osipenko wrote:
>>> External email: Use caution opening links or attachments
>>>
>>>
>>> 06.04.2020 19:12, Sowjanya Komatineni пишет:
>>>> On 4/6/20 9:05 AM, Dmitry Osipenko wrote:
>>>>> External email: Use caution opening links or attachments
>>>>>
>>>>>
>>>>> 06.04.2020 18:35, Sowjanya Komatineni пишет:
>>>>> ...
>>>>>>>> + /* wait for syncpt counter to reach frame start event
>>>>>>>> threshold */
>>>>>>>> + err = host1x_syncpt_wait(chan->frame_start_sp, thresh,
>>>>>>>> + TEGRA_VI_SYNCPT_WAIT_TIMEOUT, &value);
>>>>>>>> + if (err) {
>>>>>>>> + dev_err(&chan->video.dev,
>>>>>>>> + "frame start syncpt timeout: %d\n", err);
>>>>>>>> + /* increment syncpoint counter for timedout events */
>>>>>>>> + host1x_syncpt_incr(chan->frame_start_sp);
>>>>>>> Why incrementing is done while hardware is still active?
>>>>>>>
>>>>>>> The sync point's state needs to be completely reset after resetting
>>>>>>> hardware. But I don't think that the current upstream host1x driver
>>>>>>> supports doing that, it's one of the known-long-standing problems of
>>>>>>> the
>>>>>>> host1x driver.
>>>>>>>
>>>>>>> At least the sp->max_val incrementing should be done based on the
>>>>>>> actual
>>>>>>> syncpoint value and this should be done after resetting hardware.
>>>>>> upstream host1x driver don't have API to reset or to equalize max
>>>>>> value
>>>>>> with min/load value.
>>>>>>
>>>>>> So to synchronize missed event, incrementing HW syncpt counter.
>>>>>>
>>>>>> This should not impact as we increment this in case of missed events
>>>>>> only.
>>>>> It's wrong to touch sync point while hardware is active and it's
>>>>> active
>>>>> until being reset.
>>>>>
>>>>> You should re-check the timeout after hw resetting and manually put
>>>>> the
>>>>> syncpoint counter back into sync only if needed.
>>>> There is possibility of timeout to happen any time even during the
>>>> capture also and is not related to hw reset.
>>>>
>>>> Manual synchronization is needed when timeout of any frame events
>>>> happen
>>>> otherwise all subsequence frames will timeout due to mismatch in event
>>>> counters.
>>> My point is that hardware is stopped only after being reset, until then
>>> you should assume that sync point could be incremented by HW at any
>>> time.
>>>
>>> And if this happens that HW increments sync point after the timeout,
>>> then the sync point counter should become out-of-sync in yours case,
>>> IIUC. Because host1x_syncpt_incr() doesn't update the cached counter.
>>
>> We wait for enough time based on frame rate for syncpt increment to
>> happen and if it doesn't happen by then definitely its missed event
>> and we increment HW syncpoint for this timed event.
>>
>> cached value gets updated during syncpt wait for subsequent event.
>>
>> syncpt increment happens for all subsequent frame events during video
>> capture.
>>
> Just to be clear, syncpt max value increment happens first and syncpt
> trigger condition is programmed. hw syncpt increment happens based on HW
> events.
>
> Wait time for HW syncpt to reach threshold is tuned to work for all
> frame rates. So if increment doesn't happen by then, its definitely
> missed event.
This is questionable. Technically, speculating about whether the tuned
value is good for all possible cases is incorrect thing to do.
Although, I guess in practice it should be good enough for the starter
and could be improved later on, once the host1x driver will be improved.
> In case of missed HW event corresponding to syncpt condition, hw syncpt
> increment does not happen and driver increments it on timeout.
>
> As there is not API to equialize max with min incase of timeout/reset,
> incrementing HW syncpt for timed out event.
>
> syncpt cached value gets updated during syncpt wait when it loads from
> HW syncpt.
>
> As syncpt condition is already triggered, without compensating timeout
> events or leaving syncpt max and hw syncpt in non synchronized state for
> missed events, subsequent streamings will all timeout even on real events.
>
next prev parent reply other threads:[~2020-04-06 19:53 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 [this message]
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
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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