linux-kernel - Re: [PATCH v2 1/2] pmdomain: imx8mp-blk-ctrl: keep gpc power domain on if blk-ctrl pd is on during system pm

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Message-ID: <CAPDyKFqocghs2ucVpAz=9vErxSpCO=54RBdQg3ttoqf9t=-tYg@mail.gmail.com>
Date: Thu, 5 Feb 2026 11:56:17 +0100
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Xu Yang <xu.yang_2@....com>
Cc: Frank.Li@....com, s.hauer@...gutronix.de, kernel@...gutronix.de, 
	festevam@...il.com, peng.fan@....com, jun.li@....com, 
	rafael.j.wysocki@...el.com, a.fatoum@...gutronix.de, ping.bai@....com, 
	shawnguo@...nel.org, l.stach@...gutronix.de, linux-pm@...r.kernel.org, 
	imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] pmdomain: imx8mp-blk-ctrl: keep gpc power domain
 on if blk-ctrl pd is on during system pm

On Wed, 4 Feb 2026 at 12:10, Xu Yang <xu.yang_2@....com> wrote:
>
> Current design will power off all dependent GPC power domains in
> imx8mp_blk_ctrl_suspend(), even though the user device has enabled
> wakeup capability. The result is that wakeup function never works
> for such device.
>
> An example will be USB wakeup on i.MX8MP. PHY device '382f0040.usb-phy'
> is attached to power domain 'hsioblk-usb-phy2' which is spawned by hsio
> block control. A virtual power domain device 'genpd:3:32f10000.blk-ctrl'
> is created to build connection with 'hsioblk-usb-phy2' and it depends on
> GPC power domain 'usb-otg2'. If device '382f0040.usb-phy' enable wakeup,
> only power domain 'hsioblk-usb-phy2' keeps on during system suspend,
> power domain 'usb-otg2' is off all the time. So the wakeup event can't
> happen.
>
> In order to further establish a connection between the power domains
> related to GPC and block control during system pm, register a notifier
> to power_dev, so that GPC power domain will know that block control power
> domain is on and will not power off itself.
>
> Suggested-by: Ulf Hansson <ulf.hansson@...aro.org>
> Fixes: 556f5cf9568a ("soc: imx: add i.MX8MP HSIO blk-ctrl")
> Cc: stable@...nel.org
> Signed-off-by: Xu Yang <xu.yang_2@....com>

Applied for fixes and by amending the commit message a little bit to
make it clearer, thanks!

Kind regards
Uffe


>
> ---
> Changes in v2:
>  - add notifier to support wakeup needs
> ---
>  drivers/pmdomain/imx/imx8mp-blk-ctrl.c | 26 ++++++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
>
> diff --git a/drivers/pmdomain/imx/imx8mp-blk-ctrl.c b/drivers/pmdomain/imx/imx8mp-blk-ctrl.c
> index 34576be606e3..56bbfee8668d 100644
> --- a/drivers/pmdomain/imx/imx8mp-blk-ctrl.c
> +++ b/drivers/pmdomain/imx/imx8mp-blk-ctrl.c
> @@ -65,6 +65,7 @@ struct imx8mp_blk_ctrl_domain {
>         struct icc_bulk_data paths[DOMAIN_MAX_PATHS];
>         struct device *power_dev;
>         struct imx8mp_blk_ctrl *bc;
> +       struct notifier_block power_nb;
>         int num_paths;
>         int id;
>  };
> @@ -594,6 +595,20 @@ static int imx8mp_blk_ctrl_power_off(struct generic_pm_domain *genpd)
>         return 0;
>  }
>
> +static int imx8mp_blk_ctrl_gpc_notifier(struct notifier_block *nb,
> +                                       unsigned long action, void *data)
> +{
> +       struct imx8mp_blk_ctrl_domain *domain =
> +                       container_of(nb, struct imx8mp_blk_ctrl_domain, power_nb);
> +
> +       if (action == GENPD_NOTIFY_PRE_OFF) {
> +               if (domain->genpd.status == GENPD_STATE_ON)
> +                       return NOTIFY_BAD;
> +       }
> +
> +       return NOTIFY_OK;
> +}
> +
>  static struct lock_class_key blk_ctrl_genpd_lock_class;
>
>  static int imx8mp_blk_ctrl_probe(struct platform_device *pdev)
> @@ -698,6 +713,14 @@ static int imx8mp_blk_ctrl_probe(struct platform_device *pdev)
>                         goto cleanup_pds;
>                 }
>
> +               domain->power_nb.notifier_call = imx8mp_blk_ctrl_gpc_notifier;
> +               ret = dev_pm_genpd_add_notifier(domain->power_dev, &domain->power_nb);
> +               if (ret) {
> +                       dev_err_probe(dev, ret, "failed to add power notifier\n");
> +                       dev_pm_domain_detach(domain->power_dev, true);
> +                       goto cleanup_pds;
> +               }
> +
>                 domain->genpd.name = data->name;
>                 domain->genpd.power_on = imx8mp_blk_ctrl_power_on;
>                 domain->genpd.power_off = imx8mp_blk_ctrl_power_off;
> @@ -707,6 +730,7 @@ static int imx8mp_blk_ctrl_probe(struct platform_device *pdev)
>                 ret = pm_genpd_init(&domain->genpd, NULL, true);
>                 if (ret) {
>                         dev_err_probe(dev, ret, "failed to init power domain\n");
> +                       dev_pm_genpd_remove_notifier(domain->power_dev);
>                         dev_pm_domain_detach(domain->power_dev, true);
>                         goto cleanup_pds;
>                 }
> @@ -755,6 +779,7 @@ static int imx8mp_blk_ctrl_probe(struct platform_device *pdev)
>  cleanup_pds:
>         for (i--; i >= 0; i--) {
>                 pm_genpd_remove(&bc->domains[i].genpd);
> +               dev_pm_genpd_remove_notifier(bc->domains[i].power_dev);
>                 dev_pm_domain_detach(bc->domains[i].power_dev, true);
>         }
>
> @@ -774,6 +799,7 @@ static void imx8mp_blk_ctrl_remove(struct platform_device *pdev)
>                 struct imx8mp_blk_ctrl_domain *domain = &bc->domains[i];
>
>                 pm_genpd_remove(&domain->genpd);
> +               dev_pm_genpd_remove_notifier(domain->power_dev);
>                 dev_pm_domain_detach(domain->power_dev, true);
>         }
>
> --
> 2.34.1
>