From: Tomasz Figa <tfiga@chromium.org>
To: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Cc: linux-devicetree <devicetree@vger.kernel.org>,
"Sean Cheng (鄭昇弘)" <Sean.Cheng@mediatek.com>,
"Laurent Pinchart" <laurent.pinchart+renesas@ideasonboard.com>,
"Rynn Wu (吳育恩)" <Rynn.Wu@mediatek.com>,
zwisler@chromium.org,
srv_heupstream <srv_heupstream@mediatek.com>,
"Jerry-ch Chen" <jerry-ch.chen@mediatek.corp-partner.google.com>,
"Jerry-ch Chen" <Jerry-Ch.chen@mediatek.com>,
"Hans Verkuil" <hverkuil@xs4all.nl>,
"Jungo Lin (林明俊)" <jungo.lin@mediatek.com>,
"Sj Huang" <sj.huang@mediatek.com>,
yuzhao@chromium.org,
"moderated list:ARM/Mediatek SoC support"
<linux-mediatek@lists.infradead.org>,
"Pi-Hsun Shih" <pihsun@chromium.org>,
"Frederic Chen (陳俊元)" <frederic.chen@mediatek.com>,
"Matthias Brugger" <matthias.bgg@gmail.com>,
"Christie Yu (游雅惠)" <christie.yu@mediatek.com>,
"Mauro Carvalho Chehab" <mchehab@kernel.org>,
"list@263.net:IOMMU DRIVERS <iommu@lists.linux-foundation.org>,
Joerg Roedel <joro@8bytes.org>,
" <linux-arm-kernel@lists.infradead.org>,
"Linux Media Mailing List" <linux-media@vger.kernel.org>
Subject: Re: [RFC PATCH V4 1/4] media: v4l2-mem2mem: add v4l2_m2m_suspend, v4l2_m2m_resume
Date: Wed, 10 Jun 2020 19:03:56 +0000 [thread overview]
Message-ID: <20200610190356.GJ201868@chromium.org> (raw)
In-Reply-To: <CAAEAJfDboyra5XcEiviJP_3Kk-mDNZH5nstDa_7P7XCV7bu7Pg@mail.gmail.com>
On Wed, Jun 10, 2020 at 03:52:39PM -0300, Ezequiel Garcia wrote:
> Hi everyone,
>
> Thanks for the patch.
>
> On Wed, 10 Jun 2020 at 07:33, Tomasz Figa <tfiga@chromium.org> wrote:
> >
> > On Wed, Jun 10, 2020 at 12:29 PM Hans Verkuil <hverkuil@xs4all.nl> wrote:
> > >
> > > On 21/05/2020 19:11, Tomasz Figa wrote:
> > > > Hi Jerry,
> > > >
> > > > On Wed, Dec 04, 2019 at 08:47:29PM +0800, Jerry-ch Chen wrote:
> > > >> From: Pi-Hsun Shih <pihsun@chromium.org>
> > > >>
> > > >> Add two functions that can be used to stop new jobs from being queued /
> > > >> continue running queued job. This can be used while a driver using m2m
> > > >> helper is going to suspend / wake up from resume, and can ensure that
> > > >> there's no job running in suspend process.
[snip]
> > >
> > > I assume this will be part of a future patch series that calls these new functions?
> >
> > The mtk-jpeg encoder series depends on this patch as well, so I guess
> > it would go together with whichever is ready first.
> >
> > I would also envision someone changing the other existing drivers to
> > use the helpers, as I'm pretty much sure some of them don't handle
> > suspend/resume correctly.
> >
>
> This indeed looks very good. If I understood the issue properly,
> the change would be useful for both stateless (e.g. hantro, et al)
> and stateful (e.g. coda) codecs.
>
> Hantro uses pm_runtime_force_suspend, and I believe that
> could is enough for proper suspend/resume operation.
Unfortunately, no. :(
If the decoder is already decoding a frame, that would forcefully power
off the hardware and possibly even cause a system lockup if we are
unlucky to gate a clock in the middle of a bus transaction.
I just inspected the code now and actually found one more bug in its
power management handling. device_run() calls clk_bulk_enable() before
pm_runtime_get_sync(), but only the latter is guaranteed to actually
power on the relevant power domains, so we end up clocking unpowered
hardware.
>
> I'm not seeing any code in CODA to handle this, so not sure
> how it's handling suspend/resume.
>
> Maybe we can have CODA as the first user, given it's a well-maintained
> driver and should be fairly easy to test.
I remember checking a number of drivers using the m2m helpers randomly
and none of them implemented suspend/resume correctly. I suppose that
was not discovered because normally the userspace itself would stop the
operation before the system is suspended, although it's not an API
guarantee.
Best regards,
Tomasz
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next prev parent reply other threads:[~2020-06-10 19:04 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-04 12:47 [RFC PATCH V4 0/4] media: platform: Add support for Face Detection (FD) on mt8183 SoC Jerry-ch Chen
2019-12-04 12:47 ` [RFC PATCH V4 1/4] media: v4l2-mem2mem: add v4l2_m2m_suspend, v4l2_m2m_resume Jerry-ch Chen
2020-05-21 17:11 ` Tomasz Figa
2020-05-22 6:01 ` Jerry-ch Chen
2020-06-10 10:28 ` Hans Verkuil
2020-06-10 10:32 ` Tomasz Figa
2020-06-10 18:52 ` Ezequiel Garcia
2020-06-10 19:03 ` Tomasz Figa [this message]
2020-06-10 19:14 ` Ezequiel Garcia
2020-06-10 19:26 ` Tomasz Figa
2020-06-14 22:43 ` Ezequiel Garcia
2019-12-04 12:47 ` [RFC PATCH V4 2/4] dt-bindings: mt8183: Added FD dt-bindings Jerry-ch Chen
2019-12-04 18:58 ` Rob Herring
2020-05-06 8:41 ` Jerry-ch Chen
2019-12-04 12:47 ` [RFC PATCH V4 3/4] dts: arm64: mt8183: Add FD nodes Jerry-ch Chen
2019-12-04 12:47 ` [RFC PATCH V4 4/4] platform: mtk-isp: Add Mediatek FD driver Jerry-ch Chen
2020-05-21 18:28 ` Tomasz Figa
2020-05-22 14:10 ` Jerry-ch Chen
2020-05-25 12:24 ` Tomasz Figa
2020-05-29 12:26 ` Jerry-ch Chen
2020-05-29 12:59 ` Tomasz Figa
2020-06-01 10:37 ` Jerry-ch Chen
2020-05-08 2:02 ` [RFC PATCH V4 0/4] media: platform: Add support for Face Detection (FD) on mt8183 SoC Jerry-ch Chen
2020-05-13 21:45 ` Tomasz Figa
2020-05-21 18:38 ` Tomasz Figa
2020-06-30 14:10 ` Jerry-ch Chen
2020-06-30 17:19 ` Tomasz Figa
2020-11-11 11:51 ` Jerry-ch Chen
2020-11-12 4:26 ` Tomasz Figa
2020-11-12 12:05 ` Jerry-ch Chen
2020-12-28 17:02 ` Jerry-ch Chen
2021-01-06 6:30 ` Tomasz Figa
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