Message-ID: <97231ac9-5cde-49bf-931b-d5baf6d2d2d1@ti.com>
Date: Wed, 3 Sep 2025 13:09:41 +0530
From: Sebin Francis <sebin.francis@...com>
To: Ulf Hansson <ulf.hansson@...aro.org>,
        Saravana Kannan
	<saravanak@...gle.com>,
        Stephen Boyd <sboyd@...nel.org>, <linux-pm@...r.kernel.org>
CC: "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>, Peng Fan <peng.fan@....nxp.com>,
        Tomi Valkeinen
	<tomi.valkeinen@...asonboard.com>,
        Johan Hovold <johan@...nel.org>,
        "Maulik
 Shah" <maulik.shah@....qualcomm.com>,
        Michal Simek <michal.simek@....com>,
        Konrad Dybcio <konradybcio@...nel.org>,
        Thierry Reding
	<thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        "Hiago De
 Franco" <hiago.franco@...adex.com>,
        Geert Uytterhoeven
	<geert@...ux-m68k.org>,
        <linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 00/24] pmdomain: Add generic ->sync_state() support to
 genpd

Hi Ulf,

On 01/07/25 17:17, Ulf Hansson wrote:
> Changes in v3:
> 	- Added a couple of patches to adress problems on some Renesas
> 	platforms. Thanks Geert and Tomi for helping out!
> 	- Adressed a few comments from Saravanna and Konrad.
> 	- Added some tested-by tags.
> 
> Changes in v2:
> 	- Well, quite a lot as I discovered various problems when doing
> 	additional testing of corner-case. I suggest re-review from scratch,
> 	even if I decided to keep some reviewed-by tags.
> 	- Added patches to allow some drivers that needs to align or opt-out
> 	from the new common behaviour in genpd.
> 
> 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.
> > 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!

During testing on a TI platform, I observed new kernel warnings after 
applying this patch series:

ti_sci_pm_domains 44043000.system-controller:power-controller: 
sync_state() pending due to fd00000.gpu

These warnings occur when a device (in this case, the GPU) has no driver 
bound to it. The fw_devlink_dev_sync_state[0] in the core has a check 
before printing this warning. It checks whether the device driver has a 
sync_state handler OR the device bus has a sync_state handler in the 
dev_has_sync_state[1]. If both conditions are false, 
fw_devlink_dev_sync_state[0] performs an early return before printing 
the warning.

Before this patch series, both handlers were absent for device driver 
ti_sci_pm_domains and the device bus, so both conditions failed and no 
warnings were printed.

This patch series adds a sync_state handler for the bus, which now 
satisfies the second condition. So it doesn't do an early return and 
proceeds to print the warning.

[0]: https://elixir.bootlin.com/linux/v6.16/source/drivers/base/core.c#L1777
[1]: 
https://elixir.bootlin.com/linux/v6.16/source/include/linux/device.h#L909

Thanks
Sebin

> Finally, a big thanks to Saravana for all the support!
> 
> Kind regards
> Ulf Hansson
> 
> 
> Saravana Kannan (1):
>    driver core: Add dev_set_drv_sync_state()
> 
> Ulf Hansson (23):
>    pmdomain: renesas: rcar-sysc: Add genpd OF provider at
>      postcore_initcall
>    pmdomain: renesas: rmobile-sysc: Move init to postcore_initcall
>    pmdomain: renesas: rcar-gen4-sysc: Move init to postcore_initcall
>    pmdomain: core: Prevent registering devices before the bus
>    pmdomain: core: Add a bus and a driver for genpd providers
>    pmdomain: core: Add the genpd->dev to the genpd provider bus
>    pmdomain: core: Export a common ->sync_state() helper for genpd
>      providers
>    pmdomain: core: Prepare to add the common ->sync_state() support
>    soc/tegra: pmc: Opt-out from genpd's common ->sync_state() support
>    cpuidle: psci: Opt-out from genpd's common ->sync_state() support
>    cpuidle: riscv-sbi: Opt-out from genpd's common ->sync_state() support
>    pmdomain: qcom: rpmpd: Use of_genpd_sync_state()
>    pmdomain: qcom: rpmhpd: Use of_genpd_sync_state()
>    firmware/pmdomain: xilinx: Move ->sync_state() support to firmware
>      driver
>    firmware: xilinx: Don't share zynqmp_pm_init_finalize()
>    firmware: xilinx: Use of_genpd_sync_state()
>    driver core: Export get_dev_from_fwnode()
>    pmdomain: core: Add common ->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 late_initcall_sync
>    pmdomain: core: Leave powered-on genpds on until sync_state
>    cpuidle: psci: Drop redundant sync_state support
>    cpuidle: riscv-sbi: Drop redundant sync_state support
> 
>   drivers/base/core.c                         |   8 +-
>   drivers/cpuidle/cpuidle-psci-domain.c       |  14 --
>   drivers/cpuidle/cpuidle-riscv-sbi.c         |  14 --
>   drivers/firmware/xilinx/zynqmp.c            |  18 +-
>   drivers/pmdomain/core.c                     | 211 ++++++++++++++++++--
>   drivers/pmdomain/qcom/rpmhpd.c              |   2 +
>   drivers/pmdomain/qcom/rpmpd.c               |   2 +
>   drivers/pmdomain/renesas/rcar-gen4-sysc.c   |   2 +-
>   drivers/pmdomain/renesas/rcar-sysc.c        |  19 +-
>   drivers/pmdomain/renesas/rmobile-sysc.c     |   3 +-
>   drivers/pmdomain/xilinx/zynqmp-pm-domains.c |  16 --
>   drivers/soc/tegra/pmc.c                     |  26 ++-
>   include/linux/device.h                      |  13 ++
>   include/linux/firmware/xlnx-zynqmp.h        |   6 -
>   include/linux/pm_domain.h                   |  17 ++
>   15 files changed, 291 insertions(+), 80 deletions(-)
> 

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