From: Ulf Hansson <ulf.hansson@linaro.org>
To: Dmitry Osipenko <digetx@gmail.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>,
"Thierry Reding" <thierry.reding@gmail.com>,
"Jonathan Hunter" <jonathanh@nvidia.com>,
"Viresh Kumar" <vireshk@kernel.org>,
"Stephen Boyd" <sboyd@kernel.org>,
"Peter De Schrijver" <pdeschrijver@nvidia.com>,
"Mikko Perttunen" <mperttunen@nvidia.com>,
"Peter Chen" <peter.chen@kernel.org>,
"Lee Jones" <lee.jones@linaro.org>,
"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
"Nishanth Menon" <nm@ti.com>,
"Adrian Hunter" <adrian.hunter@intel.com>,
"Michael Turquette" <mturquette@baylibre.com>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
linux-tegra <linux-tegra@vger.kernel.org>,
"Linux PM" <linux-pm@vger.kernel.org>,
"Linux USB List" <linux-usb@vger.kernel.org>,
linux-staging@lists.linux.dev, linux-pwm@vger.kernel.org,
linux-mmc <linux-mmc@vger.kernel.org>,
dri-devel <dri-devel@lists.freedesktop.org>,
DTML <devicetree@vger.kernel.org>,
linux-clk <linux-clk@vger.kernel.org>,
"Mark Brown" <broonie@kernel.org>,
"Vignesh Raghavendra" <vigneshr@ti.com>,
"Richard Weinberger" <richard@nod.at>,
"Miquel Raynal" <miquel.raynal@bootlin.com>,
"Lucas Stach" <dev@lynxeye.de>, "Stefan Agner" <stefan@agner.ch>,
"Mauro Carvalho Chehab" <mchehab@kernel.org>,
"David Heidelberg" <david@ixit.cz>
Subject: Re: [PATCH v13 13/35] drm/tegra: gr2d: Support generic power domain and runtime PM
Date: Mon, 4 Oct 2021 13:01:01 +0200 [thread overview]
Message-ID: <CAPDyKFpqs5gUcym4q+GuiJy13eXqjEnx-eFdUT4bQpcfPAOEYw@mail.gmail.com> (raw)
In-Reply-To: <8d75436d-864a-7ce0-ba53-daa8b663035a@gmail.com>
On Fri, 1 Oct 2021 at 21:00, Dmitry Osipenko <digetx@gmail.com> wrote:
>
> 01.10.2021 17:55, Ulf Hansson пишет:
> > On Fri, 1 Oct 2021 at 16:29, Dmitry Osipenko <digetx@gmail.com> wrote:
> >>
> >> 01.10.2021 16:39, Ulf Hansson пишет:
> >>> On Mon, 27 Sept 2021 at 00:42, Dmitry Osipenko <digetx@gmail.com> wrote:
> >>>>
> >>>> Add runtime power management and support generic power domains.
> >>>>
> >>>> Tested-by: Peter Geis <pgwipeout@gmail.com> # Ouya T30
> >>>> Tested-by: Paul Fertser <fercerpav@gmail.com> # PAZ00 T20
> >>>> Tested-by: Nicolas Chauvet <kwizart@gmail.com> # PAZ00 T20 and TK1 T124
> >>>> Tested-by: Matt Merhar <mattmerhar@protonmail.com> # Ouya T30
> >>>> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> >>>> ---
> >>>> drivers/gpu/drm/tegra/gr2d.c | 155 +++++++++++++++++++++++++++++++++--
> >>>
> >>> [...]
> >>>
> >>>> static int gr2d_remove(struct platform_device *pdev)
> >>>> @@ -259,15 +312,101 @@ static int gr2d_remove(struct platform_device *pdev)
> >>>> return err;
> >>>> }
> >>>>
> >>>> + pm_runtime_dont_use_autosuspend(&pdev->dev);
> >>>> + pm_runtime_disable(&pdev->dev);
> >>>
> >>> There is no guarantee that the ->runtime_suspend() has been invoked
> >>> here, which means that clock may be left prepared/enabled beyond this
> >>> point.
> >>>
> >>> I suggest you call pm_runtime_force_suspend(), instead of
> >>> pm_runtime_disable(), to make sure that gets done.
> >>
> >> The pm_runtime_disable() performs the final synchronization, please see [1].
> >>
> >> [1]
> >> https://elixir.bootlin.com/linux/v5.15-rc3/source/drivers/base/power/runtime.c#L1412
> >
> > pm_runtime_disable() end up calling _pm_runtime_barrier(), which calls
> > cancel_work_sync() if dev->power.request_pending has been set.
> >
> > If the work that was punted to the pm_wq in rpm_idle() has not been
> > started yet, we end up just canceling it. In other words, there are no
> > guarantees it runs to completion.
>
> You're right. Although, in a case of this particular patch, the syncing
> is actually implicitly done by pm_runtime_dont_use_autosuspend().
>
> But for drivers which don't use auto-suspend, there is no sync. This
> looks like a disaster, it's a very common pattern for drivers to
> 'put+disable'.
>
> > Moreover, use space may have bumped the usage count via sysfs for the
> > device (pm_runtime_forbid()) to keep the device runtime resumed.
>
> Right, this is also a disaster in a case of driver removal.
>
> >> Calling pm_runtime_force_suspend() isn't correct because each 'enable'
> >> must have the corresponding 'disable'. Hence there is no problem here.
> >
> > pm_runtime_force_suspend() calls pm_runtime_disable(), so I think that
> > should be fine. No?
>
> [adding Rafael]
>
> Rafael, could you please explain how drivers are supposed to properly
> suspend and disable RPM to cut off power and reset state that was
> altered by the driver's resume callback? What we're missing? Is Ulf's
> suggestion acceptable?
>
> The RPM state of a device is getting reset on driver's removal, hence
> all refcounts that were bumped by the rpm-resume callback of the device
> driver will be screwed up if device is kept resumed after removal. I
> just verified that it's true in practice.
Note that, what makes the Tegra drivers a bit special is that they are
always built with CONFIG_PM being set (selected from the "SoC"
Kconfig).
Therefore, pm_runtime_force_suspend() can work for some of these
cases. Using this, would potentially avoid the driver from having to
runtime resume the device in ->remove(), according to the below
generic sequence, which is used in many drivers.
pm_runtime_get_sync()
clk_disable_unprepare() (+ additional things to turn off the device)
pm_runtime_disable()
pm_runtime_put_noidle()
Kind regards
Uffe
next prev parent reply other threads:[~2021-10-04 11:01 UTC|newest]
Thread overview: 83+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-26 22:40 [PATCH v13 00/35] NVIDIA Tegra power management patches for 5.16 Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 01/35] opp: Change type of dev_pm_opp_attach_genpd(names) argument Dmitry Osipenko
2021-10-04 9:11 ` Viresh Kumar
2021-09-26 22:40 ` [PATCH v13 02/35] soc/tegra: Add devm_tegra_core_dev_init_opp_table_common() Dmitry Osipenko
2021-10-01 12:50 ` Ulf Hansson
2021-10-01 19:15 ` Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 03/35] soc/tegra: pmc: Disable PMC state syncing Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 04/35] soc/tegra: Don't print error message when OPPs not available Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 05/35] dt-bindings: clock: tegra-car: Document new clock sub-nodes Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 06/35] clk: tegra: Support runtime PM and power domain Dmitry Osipenko
2021-10-01 12:32 ` Ulf Hansson
2021-10-01 19:50 ` Dmitry Osipenko
2021-10-02 20:44 ` Dmitry Osipenko
2021-10-05 13:10 ` Ulf Hansson
2021-10-05 22:19 ` Dmitry Osipenko
2021-10-05 22:43 ` Dmitry Osipenko
2021-10-06 2:40 ` Dmitry Osipenko
2021-10-06 12:43 ` Ulf Hansson
2021-10-06 21:14 ` Dmitry Osipenko
2021-10-06 22:01 ` Dmitry Osipenko
2021-10-06 23:21 ` Dmitry Osipenko
2021-10-07 9:18 ` Ulf Hansson
2021-10-07 10:36 ` Dmitry Osipenko
2021-10-06 12:38 ` Ulf Hansson
2021-10-06 21:20 ` Dmitry Osipenko
2021-10-06 21:25 ` Dmitry Osipenko
2021-10-06 22:03 ` Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 07/35] dt-bindings: host1x: Document OPP and power domain properties Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 08/35] dt-bindings: host1x: Document Memory Client resets of Host1x, GR2D and GR3D Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 09/35] gpu: host1x: Add runtime PM and OPP support Dmitry Osipenko
2021-10-01 13:24 ` Ulf Hansson
2021-09-26 22:40 ` [PATCH v13 10/35] gpu: host1x: Add host1x_channel_stop() Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 11/35] drm/tegra: dc: Support OPP and SoC core voltage scaling Dmitry Osipenko
2021-10-01 13:27 ` Ulf Hansson
2021-10-16 15:36 ` Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 12/35] drm/tegra: hdmi: Add OPP support Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 13/35] drm/tegra: gr2d: Support generic power domain and runtime PM Dmitry Osipenko
2021-10-01 13:39 ` Ulf Hansson
2021-10-01 14:29 ` Dmitry Osipenko
2021-10-01 14:55 ` Ulf Hansson
2021-10-01 19:00 ` Dmitry Osipenko
2021-10-04 11:01 ` Ulf Hansson [this message]
2021-10-04 15:57 ` Dmitry Osipenko
2021-10-05 8:45 ` Ulf Hansson
2021-10-05 17:16 ` Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 14/35] drm/tegra: gr3d: " Dmitry Osipenko
2021-10-01 14:06 ` Ulf Hansson
2021-10-01 21:25 ` Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 15/35] drm/tegra: vic: Support system suspend Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 16/35] usb: chipidea: tegra: Add runtime PM and OPP support Dmitry Osipenko
2021-09-30 0:40 ` Dmitry Osipenko
2021-09-30 14:06 ` Peter Chen
2021-09-30 14:08 ` Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 17/35] bus: tegra-gmi: " Dmitry Osipenko
2021-10-01 14:18 ` Ulf Hansson
2021-09-26 22:40 ` [PATCH v13 18/35] pwm: tegra: " Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 19/35] mmc: sdhci-tegra: " Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 20/35] mtd: rawnand: tegra: " Dmitry Osipenko
2021-10-01 14:24 ` Ulf Hansson
2021-10-01 14:35 ` Dmitry Osipenko
2021-10-01 15:01 ` Ulf Hansson
2021-10-17 8:38 ` Dmitry Osipenko
2021-10-19 11:40 ` Ulf Hansson
2021-09-26 22:40 ` [PATCH v13 21/35] spi: tegra20-slink: Add " Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 22/35] media: dt: bindings: tegra-vde: Convert to schema Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 23/35] media: dt: bindings: tegra-vde: Document OPP and power domain Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 24/35] media: staging: tegra-vde: Support generic " Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 25/35] soc/tegra: fuse: Reset hardware Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 26/35] soc/tegra: fuse: Use resource-managed helpers Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 27/35] soc/tegra: regulators: Prepare for suspend Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 28/35] soc/tegra: pmc: Rename 3d power domains Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 29/35] soc/tegra: pmc: Rename core power domain Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 30/35] soc/tegra: pmc: Enable core domain support for Tegra20 and Tegra30 Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 31/35] ARM: tegra: Add OPP tables and power domains to Tegra20 device-trees Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 32/35] ARM: tegra: Add OPP tables and power domains to Tegra30 device-trees Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 33/35] ARM: tegra: Add Memory Client resets to Tegra20 GR2D, GR3D and Host1x Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 34/35] ARM: tegra: Add Memory Client resets to Tegra30 " Dmitry Osipenko
2021-09-26 22:40 ` [PATCH v13 35/35] ARM: tegra20/30: Disable unused host1x hardware Dmitry Osipenko
2021-10-01 14:36 ` [PATCH v13 00/35] NVIDIA Tegra power management patches for 5.16 Ulf Hansson
2021-10-01 14:40 ` Dmitry Osipenko
2021-10-01 15:02 ` Ulf Hansson
2021-10-04 9:11 ` Viresh Kumar
2021-10-04 14:52 ` Dmitry Osipenko
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAPDyKFpqs5gUcym4q+GuiJy13eXqjEnx-eFdUT4bQpcfPAOEYw@mail.gmail.com \
--to=ulf.hansson@linaro.org \
--cc=adrian.hunter@intel.com \
--cc=broonie@kernel.org \
--cc=david@ixit.cz \
--cc=dev@lynxeye.de \
--cc=devicetree@vger.kernel.org \
--cc=digetx@gmail.com \
--cc=dri-devel@lists.freedesktop.org \
--cc=jonathanh@nvidia.com \
--cc=lee.jones@linaro.org \
--cc=linux-clk@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mmc@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=linux-pwm@vger.kernel.org \
--cc=linux-staging@lists.linux.dev \
--cc=linux-tegra@vger.kernel.org \
--cc=linux-usb@vger.kernel.org \
--cc=mchehab@kernel.org \
--cc=miquel.raynal@bootlin.com \
--cc=mperttunen@nvidia.com \
--cc=mturquette@baylibre.com \
--cc=nm@ti.com \
--cc=pdeschrijver@nvidia.com \
--cc=peter.chen@kernel.org \
--cc=rafael@kernel.org \
--cc=richard@nod.at \
--cc=sboyd@kernel.org \
--cc=stefan@agner.ch \
--cc=thierry.reding@gmail.com \
--cc=u.kleine-koenig@pengutronix.de \
--cc=vigneshr@ti.com \
--cc=vireshk@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).