[PATCH v5 3/3] remoteproc: imx_rproc: detect and attach to pre-booted remote cores

[Ulf Hansson]

On Tue, 17 Jun 2025 at 21:36, Hiago De Franco <hiagofranco at gmail.com> wrote:
>
> From: Hiago De Franco <hiago.franco at toradex.com>
>
> When the remote core is started before Linux boots (e.g., by the
> bootloader), the driver currently is not able to attach because it only
> checks for cores running in different partitions. If the core was kicked
> by the bootloader, it is in the same partition as Linux and it is
> already up and running.
>
> This adds power mode verification through dev_pm_genpd_is_on(), enabling
> the driver to detect when the remote core is already running and
> properly attach to it if all the power domain devices are on.
>
> To accomplish this, we need to avoid passing any attach_data or flags to
> dev_pm_domain_attach_list(), letting the platform device become a
> consumer of the power domain provider. With that the current power state
> of the genpds will not change, allowing the detection of the remote core
> power state.
>
> We enable and sync the device runtime PM during probe to make sure the
> power domains are correctly managed when the core is controlled by the
> kernel.
>
> Suggested-by: Ulf Hansson <ulf.hansson at linaro.org>
> Signed-off-by: Hiago De Franco <hiago.franco at toradex.com>

Reviewed-by: Ulf Hansson <ulf.hansson at linaro.org>

Kind regards
Uffe

> ---
> v4 -> v5:
>  - pm_runtime_get_sync() removed in favor of
>    pm_runtime_resume_and_get(). Now it also checks the return value of
>    this function.
>  - Added pm_runtime_disable() and pm_runtime_put() to imx_rproc_remove()
>    function.
> v3 -> v4:
>  - Changed to use the new dev_pm_genpd_is_on() function instead, as
>    suggested by Ulf. This will now get the power status of the two
>    remote cores power domains to decided if imx_rpoc needs to attach or
>    not. In order to do that, pm_runtime_enable() and
>    pm_runtime_get_sync() were introduced and pd_data was removed.
> v2 -> v3:
>  - Unchanged.
> v1 -> v2:
>  - Dropped unecessary include. Removed the imx_rproc_is_on function, as
>    suggested.
> ---
>  drivers/remoteproc/imx_rproc.c | 37 +++++++++++++++++++++++++++++-----
>  1 file changed, 32 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/remoteproc/imx_rproc.c b/drivers/remoteproc/imx_rproc.c
> index 627e57a88db2..b53083f2553e 100644
> --- a/drivers/remoteproc/imx_rproc.c
> +++ b/drivers/remoteproc/imx_rproc.c
> @@ -18,6 +18,7 @@
>  #include <linux/of_reserved_mem.h>
>  #include <linux/platform_device.h>
>  #include <linux/pm_domain.h>
> +#include <linux/pm_runtime.h>
>  #include <linux/reboot.h>
>  #include <linux/regmap.h>
>  #include <linux/remoteproc.h>
> @@ -890,10 +891,8 @@ static int imx_rproc_partition_notify(struct notifier_block *nb,
>  static int imx_rproc_attach_pd(struct imx_rproc *priv)
>  {
>         struct device *dev = priv->dev;
> -       int ret;
> -       struct dev_pm_domain_attach_data pd_data = {
> -               .pd_flags = PD_FLAG_DEV_LINK_ON,
> -       };
> +       int ret, i;
> +       bool detached = true;
>
>         /*
>          * If there is only one power-domain entry, the platform driver framework
> @@ -902,7 +901,22 @@ static int imx_rproc_attach_pd(struct imx_rproc *priv)
>         if (dev->pm_domain)
>                 return 0;
>
> -       ret = dev_pm_domain_attach_list(dev, &pd_data, &priv->pd_list);
> +       ret = dev_pm_domain_attach_list(dev, NULL, &priv->pd_list);
> +       /*
> +        * If all the power domain devices are already turned on, the remote
> +        * core is already up when the kernel booted (e.g. kicked by the
> +        * bootloader). In this case attach to it.
> +        */
> +       for (i = 0; i < ret; i++) {
> +               if (!dev_pm_genpd_is_on(priv->pd_list->pd_devs[i])) {
> +                       detached = false;
> +                       break;
> +               }
> +       }
> +
> +       if (detached)
> +               priv->rproc->state = RPROC_DETACHED;
> +
>         return ret < 0 ? ret : 0;
>  }
>
> @@ -1146,6 +1160,15 @@ static int imx_rproc_probe(struct platform_device *pdev)
>                 }
>         }
>
> +       if (dcfg->method == IMX_RPROC_SCU_API) {
> +               pm_runtime_enable(dev);
> +               ret = pm_runtime_resume_and_get(dev);
> +               if (ret) {
> +                       dev_err(dev, "pm_runtime get failed: %d\n", ret);
> +                       goto err_put_clk;
> +               }
> +       }
> +
>         ret = rproc_add(rproc);
>         if (ret) {
>                 dev_err(dev, "rproc_add failed\n");
> @@ -1171,6 +1194,10 @@ static void imx_rproc_remove(struct platform_device *pdev)
>         struct rproc *rproc = platform_get_drvdata(pdev);
>         struct imx_rproc *priv = rproc->priv;
>
> +       if (priv->dcfg->method == IMX_RPROC_SCU_API) {
> +               pm_runtime_disable(priv->dev);
> +               pm_runtime_put(priv->dev);
> +       }
>         clk_disable_unprepare(priv->clk);
>         rproc_del(rproc);
>         imx_rproc_put_scu(rproc);
> --
> 2.39.5
>