linux-kernel - Re: [PATCH v4 0/4] watchdog: rzg2l_wdt: Enable properly the watchdog clocks and power domain

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Message-ID: <CAPDyKFq1-fW=d5QiEcYNkErpMuBo0aZzB1pos1CHcPZmAWGTRw@mail.gmail.com>
Date: Fri, 18 Oct 2024 10:49:58 +0200
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Claudiu <claudiu.beznea@...on.dev>
Cc: geert+renesas@...der.be, mturquette@...libre.com, sboyd@...nel.org, 
	wim@...ux-watchdog.org, linux@...ck-us.net, linux-renesas-soc@...r.kernel.org, 
	linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-watchdog@...r.kernel.org, linux-pm@...r.kernel.org, 
	Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: Re: [PATCH v4 0/4] watchdog: rzg2l_wdt: Enable properly the watchdog
 clocks and power domain

On Tue, 15 Oct 2024 at 18:47, Claudiu <claudiu.beznea@...on.dev> wrote:
>
> From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
>
> Hi,
>
> Watchdog device available on RZ/G3S SoC is part of a software-controlled
> power domain. The watchdog driver implements struct
> watchdog_ops::restart() handler which is called in atomic context via
> this call chain:
>
> kernel_restart() ->
>   machine_restart() ->
>     do_kernel_restart() ->
>       atomic_notifier_call_chain() ->
>         watchdog_restart_notifier()
>           rzg2l_wdt_restart()
>
> When the rzg2l_wdt_restart() is called it may happen that the watchdog
> clocks to be disabled and the associated power domain to be off.
> Accessing watchdog registers in this state leads to aborts and system
> blocks.
>
> To solve this issue the watchdog power domain was marked as IRQ safe
> as well as watchdog device (as proposed by Ulf Hansson). Along with
> it the clk_prepare_enable() calls from the watchdog restart() handler
> were removed and all is based now on pm_runtime_resume_and_get()
> as explained in patch 03/03.
>
> Series contains also power domain driver changes to be able to
> register the watchdog PM domain as an IRQ safe one.
>
> Initial RFC series for solving this issue was posted at [1].
>
> It is safe to merge watchdog and PM domain driver changes though
> different trees.
>
> Thank you,
> Claudiu Beznea
>
> [1] https://lore.kernel.org/all/20240619120920.2703605-1-claudiu.beznea.uj@bp.renesas.com/
>
> Changes in v4:
> - in patch 1/1, function rzg2l_cpg_pd_setup():
> -- call rzg2l_cpg_power_on() unconditionally of governor
> -- drop governor's parameter and decide what governor to use based on
>    always_on
> - collected tags
>
> Changes in v3:
> - added patch "clk: renesas: rzg2l-cpg: Move PM domain power on in
>   rzg2l_cpg_pd_setup()"
> - addressed review comments
> - collected tags
> - per-patch changes are listed in individual patches
>
> Changes in v2:
> - adjusted patch title for patch 02/03
> - adjusted description for patch 03/03 along with comment
>   from code
>
> Changes since RFC:
> - dropped patches 01/03, 02/03 from RFC
> - adjusted power domain driver to be able to register the
>   watchdog PM domain as an IRQ safe one
> - drop clock prepare approach from watchdog driver presented in RFC
>   and rely only on pm_runtime_resume_and_get()
> - mark the watchdog device as IRQ safe
>
>
> Claudiu Beznea (4):
>   clk: renesas: rzg2l-cpg: Move PM domain power on in
>     rzg2l_cpg_pd_setup()
>   clk: renesas: rzg2l-cpg: Use GENPD_FLAG_* flags instead of local ones
>   clk: renesas: r9a08g045: Mark the watchdog and always-on PM domains as
>     IRQ safe
>   watchdog: rzg2l_wdt: Power on the watchdog domain in the restart
>     handler
>
>  drivers/clk/renesas/r9a08g045-cpg.c | 52 +++++++++++------------------
>  drivers/clk/renesas/rzg2l-cpg.c     | 41 ++++++++++++-----------
>  drivers/clk/renesas/rzg2l-cpg.h     | 10 ++----
>  drivers/watchdog/rzg2l_wdt.c        | 20 +++++++++--
>  4 files changed, 63 insertions(+), 60 deletions(-)
>
> --
> 2.39.2
>

For the series, feel free to add:

Reviewed-by: Ulf Hansson <ulf.hansson@...aro.org>

Kind regards
Uffe