linux-kernel - Re: [PATCH v3 08/10] pmdomain: samsung: selectively handle enforced sync

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Message-ID: <CAPDyKFq2esPos=D-eVz6w1VXq=4LYi6fx54K4TvsUi4JqUJOaQ@mail.gmail.com>
Date: Wed, 22 Oct 2025 13:06:59 +0200
From: Ulf Hansson <ulf.hansson@...aro.org>
To: André Draszik <andre.draszik@...aro.org>
Cc: Krzysztof Kozlowski <krzk@...nel.org>, Alim Akhtar <alim.akhtar@...sung.com>, 
	Rob Herring <robh@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Marek Szyprowski <m.szyprowski@...sung.com>, 
	Peter Griffin <peter.griffin@...aro.org>, Tudor Ambarus <tudor.ambarus@...aro.org>, 
	Will McVicker <willmcvicker@...gle.com>, kernel-team@...roid.com, 
	linux-arm-kernel@...ts.infradead.org, linux-samsung-soc@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-pm@...r.kernel.org
Subject: Re: [PATCH v3 08/10] pmdomain: samsung: selectively handle enforced sync_state

On Thu, 16 Oct 2025 at 17:58, André Draszik <andre.draszik@...aro.org> wrote:
>
> Unconditionally calling of_genpd_sync_state() causes issues on
> platforms with child domains as the parent domain will be turned off
> before the child domain was even registered during boot.
>
> This in particular is an issue for the upcoming Google gs101 support -
> all operations on child domains registered after the parent domain
> misbehave.
>
> Add a flag to the probe data to be able to sync_state conditionally
> only, and enable that flag on the two platforms currently supported by
> this driver.
>
> Signed-off-by: André Draszik <andre.draszik@...aro.org>
>
> ---
> v2:
> * use bool for need_early_sync_state (Krzysztof)
> ---
>  drivers/pmdomain/samsung/exynos-pm-domains.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pmdomain/samsung/exynos-pm-domains.c b/drivers/pmdomain/samsung/exynos-pm-domains.c
> index 638d286b57f716140b2401092415644a6805870e..15a1582aa92103a07335eb681600d9415369fefd 100644
> --- a/drivers/pmdomain/samsung/exynos-pm-domains.c
> +++ b/drivers/pmdomain/samsung/exynos-pm-domains.c
> @@ -20,6 +20,7 @@
>  struct exynos_pm_domain_config {
>         /* Value for LOCAL_PWR_CFG and STATUS fields for each domain */
>         u32 local_pwr_cfg;
> +       bool need_early_sync_state;
>  };
>
>  /*
> @@ -69,10 +70,12 @@ static int exynos_pd_power_off(struct generic_pm_domain *domain)
>
>  static const struct exynos_pm_domain_config exynos4210_cfg = {
>         .local_pwr_cfg          = 0x7,
> +       .need_early_sync_state  = true,
>  };
>
>  static const struct exynos_pm_domain_config exynos5433_cfg = {
>         .local_pwr_cfg          = 0xf,
> +       .need_early_sync_state  = true,
>  };
>
>  static const struct of_device_id exynos_pm_domain_of_match[] = {
> @@ -179,7 +182,7 @@ static int exynos_pd_probe(struct platform_device *pdev)
>          * reset during boot. As a temporary hack to manage this, let's enforce
>          * a sync_state.
>          */
> -       if (!ret)
> +       if (pm_domain_cfg->need_early_sync_state && !ret)
>                 of_genpd_sync_state(np);

The call to of_genpd_sync_state() was intended as a temporary solution here.

Potentially, if we would be able to distinguish what PM domain that is
causing the problem on the Exynos platforms, we could set
GENPD_FLAG_NO_STAY_ON for that genpd instead.

>
>         pm_runtime_enable(dev);
>
> --
> 2.51.0.788.g6d19910ace-goog
>

The above said, $subject patch is still fine as is for me.

Kind regards
Uffe