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

[Hiago De Franco <hiagofranco@gmail.com>]

On Mon, Jun 23, 2025 at 09:29:47AM -0600, Mathieu Poirier wrote:
> On Tue, Jun 17, 2025 at 04:34:50PM -0300, Hiago De Franco wrote:
> > From: Hiago De Franco <hiago.franco@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
> 
> Again, we have a nomenclature issue here with "If the core was kicked by the
> bootloader".  What does "kicked" mean here?  Is it just powered and held in
> reset or is it executing.  And are you referring to the A core or the M core?

Ok, same here, I will improve this in the next revision. Thanks.

> 
> 
> > 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@linaro.org>
> > Signed-off-by: Hiago De Franco <hiago.franco@toradex.com>
> > ---
> > 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.
> 
> Same comment as above.  What got kicked?  A core or M core.  And what does
> "kicked" mean?  I can guess what is happening but guessing rarely leads to
> anything positive.
> 
> In the next revision, please use other words than "kicked".

Noted, thanks.

> 
> 
> > +	 */
> > +	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;
> > +
> 
> Ok for the above.
> 
> >  	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
> >