linux-kernel - Re: [PATCH 00/11] pmdomain: Add generic ->sync

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Message-ID: <CAGETcx_=hEuOs09=gRe58+34PFa0bfsYoAK9kYOn90FP5nDjmw@mail.gmail.com>
Date: Thu, 17 Apr 2025 17:53:36 -0700
From: Saravana Kannan <saravanak@...gle.com>
To: Ulf Hansson <ulf.hansson@...aro.org>
Cc: Stephen Boyd <sboyd@...nel.org>, linux-pm@...r.kernel.org, 
	"Rafael J . Wysocki" <rafael@...nel.org>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
	Michael Grzeschik <m.grzeschik@...gutronix.de>, Bjorn Andersson <andersson@...nel.org>, 
	Abel Vesa <abel.vesa@...aro.org>, Devarsh Thakkar <devarsht@...v0571a.ent.ti.com>, 
	Peng Fan <peng.fan@....nxp.com>, Tomi Valkeinen <tomi.valkeinen@...asonboard.com>, 
	Johan Hovold <johan@...nel.org>, Maulik Shah <maulik.shah@....qualcomm.com>, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 00/11] pmdomain: Add generic ->sync_state() support to genpd

On Thu, Apr 17, 2025 at 7:25 AM Ulf Hansson <ulf.hansson@...aro.org> wrote:
>
> If a PM domain (genpd) is powered-on during boot, there is probably a good
> reason for it. Therefore it's known to be a bad idea to allow such genpd to be
> powered-off before all of its consumer devices have been probed. This series
> intends to fix this problem.
>
> We have been discussing these issues at LKML and at various Linux-conferences
> in the past. I have therefore tried to include the people I can recall being
> involved, but I may have forgotten some (my apologies), feel free to loop them
> in.
>
> A few notes:
> *)
> Even if this looks good, the last patch can't go in without some additional
> changes to a couple of existing genpd provider drivers. Typically genpd provider
> drivers that implements ->sync_state() need to call of_genpd_sync_state(), but I
> will fix this asap, if we think the series makes sense.
>
> *)
> Patch 1 -> 3 are just preparatory cleanups.
>
> *)
> I have tested this with QEMU with a bunch of local test-drivers and DT nodes.
> Let me know if you want me to share this code too.
>
>
> Please help review and test!
> Finally, a big thanks to Saravana for all the support!

You are welcome! Thank you for getting this series done! Happy to see
sync_state() support being added to another framework.

I skimmed the series and at a high level it looks right. Not too
familiar with power domain code, so I didn't go deep. Just reviewed
the fw_devlink and driver core parts of it.

-Saravana

>
> Kind regards
> Ulf Hansson
>
>
> Saravana Kannan (1):
>   driver core: Add dev_set_drv_sync_state()
>
> Ulf Hansson (10):
>   pmdomain: core: Convert genpd_power_off() to void
>   pmdomain: core: Simplify return statement in genpd_power_off()
>   pmdomain: core: Use genpd->opp_table to simplify error/remove path
>   pmdomain: core: Add a bus and a driver for genpd providers
>   pmdomain: core: Use device_set_node() to assign the fwnode too
>   pmdomain: core: Add the genpd->dev to the genpd provider bus
>   pmdomain: core: Export a common ->sync_state() helper for genpd
>     providers
>   pmdomain: core: Add internal ->sync_state() support for genpd
>     providers
>   pmdomain: core: Default to use of_genpd_sync_state() for genpd
>     providers
>   pmdomain: core: Leave powered-on genpds on until ->sync_state()
>
>  drivers/pmdomain/core.c   | 273 +++++++++++++++++++++++++++++++-------
>  include/linux/device.h    |  12 ++
>  include/linux/pm_domain.h |  11 ++
>  3 files changed, 249 insertions(+), 47 deletions(-)
>
> --
> 2.43.0
>