linux-kernel - Re: [PATCH v2 3/3] remoteproc: imx_rproc: add power mode check for remote core attachment

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Message-ID: <CAPDyKFrHD1hVCfOK-JV5FJM+Cd9DoKKZGKcC94fxx6_9Bsri1g@mail.gmail.com>
Date: Thu, 8 May 2025 12:03:33 +0200
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Hiago De Franco <hiagofranco@...il.com>
Cc: Mathieu Poirier <mathieu.poirier@...aro.org>, linux-pm@...r.kernel.org, 
	linux-remoteproc@...r.kernel.org, Shawn Guo <shawnguo@...nel.org>, 
	Sascha Hauer <s.hauer@...gutronix.de>, Bjorn Andersson <andersson@...nel.org>, 
	Hiago De Franco <hiago.franco@...adex.com>, imx@...ts.linux.dev, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	Peng Fan <peng.fan@....nxp.com>, daniel.baluta@....com, iuliana.prodan@....nxp.com, 
	Fabio Estevam <festevam@...il.com>, Pengutronix Kernel Team <kernel@...gutronix.de>, Peng Fan <peng.fan@....com>
Subject: Re: [PATCH v2 3/3] remoteproc: imx_rproc: add power mode check for
 remote core attachment

On Wed, 7 May 2025 at 18:02, Hiago De Franco <hiagofranco@...il.com> wrote:
>
> From: Hiago De Franco <hiago.franco@...adex.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 the SCU interface, enabling
> the driver to detect when the remote core is already running and
> properly attach to it.
>
> Signed-off-by: Hiago De Franco <hiago.franco@...adex.com>
> Suggested-by: Peng Fan <peng.fan@....com>
> ---
> v2: Dropped unecessary include. Removed the imx_rproc_is_on function, as
> suggested.
> ---
>  drivers/remoteproc/imx_rproc.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
>
> diff --git a/drivers/remoteproc/imx_rproc.c b/drivers/remoteproc/imx_rproc.c
> index 627e57a88db2..9b6e9e41b7fc 100644
> --- a/drivers/remoteproc/imx_rproc.c
> +++ b/drivers/remoteproc/imx_rproc.c
> @@ -949,6 +949,19 @@ static int imx_rproc_detect_mode(struct imx_rproc *priv)
>                         if (of_property_read_u32(dev->of_node, "fsl,entry-address", &priv->entry))
>                                 return -EINVAL;
>
> +                       /*
> +                        * If remote core is already running (e.g. kicked by
> +                        * the bootloader), attach to it.
> +                        */
> +                       ret = imx_sc_pm_get_resource_power_mode(priv->ipc_handle,
> +                                                               priv->rsrc_id);
> +                       if (ret < 0)
> +                               dev_err(dev, "failed to get power resource %d mode, ret %d\n",
> +                                       priv->rsrc_id, ret);
> +
> +                       if (ret == IMX_SC_PM_PW_MODE_ON)
> +                               priv->rproc->state = RPROC_DETACHED;
> +
>                         return imx_rproc_attach_pd(priv);

Why is it important to potentially set "priv->rproc->state =
RPROC_DETACHED" before calling imx_rproc_attach_pd()?

Would it be possible to do it the other way around? First calling
imx_rproc_attach_pd() then get the power-mode to know if
RPROC_DETACHED should be set or not?

The main reason why I ask, is because of how we handle the single PM
domain case. In that case, the PM domain has already been attached
(and powered-on) before we reach this point.

>                 }
>
> --
> 2.39.5
>

Kind regards
Uffe