Re: [PATCH v7 3/3] remoteproc: imx_rproc: detect and attach to pre-booted remote cores

Hiago De Franco
2025-07-16T13:28:52Z

Hi Mathieu, Ulf,

On Tue, Jul 15, 2025 at 09:32:44AM -0600, Mathieu Poirier wrote:
> On Sun, Jun 29, 2025 at 02:25:12PM -0300, Hiago De Franco wrote:
> > From: Hiago De Franco <hiago.franco@toradex.com>
> >
> > When the Cortex-M remote core is started and already running before
> > Linux boots (typically by the Cortex-A bootloader using a command like
> > bootaux), the current driver is unable to attach to it. This is because
> > the driver only checks for remote cores running in different SCFW
> > partitions. However in this case, the M-core is in the same partition as
> > Linux and is already powered up and running by the bootloader.
> >
> > This patch adds a check using dev_pm_genpd_is_on() to verify whether the
> > M-core's power domains are already on. If all power domain devices are
> > on, the driver assumes the M-core is running and proceed to attach to
> > it.
> >
> > To accomplish this, we need to avoid passing any attach_data or flags to
> > dev_pm_domain_attach_list(), allowing the platform device become a
> > consumer of the power domain provider without changing its current
> > state.
> >
> > During probe, also enable and sync the device runtime PM 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>
> > Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
> > Reviewed-by: Peng Fan <peng.fan@nxp.com>
> > Signed-off-by: Hiago De Franco <hiago.franco@toradex.com>
> > ---
> > v6 -> v7:
> > - Added Peng reviewed-by.
> > v5 -> v6:
> > - Commit description improved, as suggested. Added Ulf Hansson reviewed
> > by. Comment on imx-rproc.c improved.
> > 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..24597b60c5b0 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 powered up and running when the kernel booted (e.g.,
> > + * started by U-Boot's bootaux command). 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;
> > + }
> > + }
>
> I was doing one final review of this work when I noticed the return code for
> dev_pm_domain_attach_list() is never checked for error.

As Ulf pointed out, the 'return' a few lines below will return the
negative value to the caller of 'imx_rproc_attach_pd', which ultimately
will fail 'imx_rproc_detect_mode' and fail the probe of imx_rproc.

Please notice that even tough 'dev_pm_domain_attach_list' fails, the
rproc->state will still be set as RPROC_DETACHED because we are starting
'detached' as true, but I am not seeing this as an issue because as
mentioned above the probe will fail anyway. Please let me know if you
see this as an issue.

>
> Thanks,
> Mathieu
>
> > +
> > + 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
> >

On Tue, Jul 15, 2025 at 06:03:44PM +0200, Ulf Hansson wrote:
> On Tue, 15 Jul 2025 at 17:32, Mathieu Poirier
> <mathieu.poirier@linaro.org> wrote:
> >
> > On Sun, Jun 29, 2025 at 02:25:12PM -0300, Hiago De Franco wrote:
> > > From: Hiago De Franco <hiago.franco@toradex.com>
> > >
> > > When the Cortex-M remote core is started and already running before
> > > Linux boots (typically by the Cortex-A bootloader using a command like
> > > bootaux), the current driver is unable to attach to it. This is because
> > > the driver only checks for remote cores running in different SCFW
> > > partitions. However in this case, the M-core is in the same partition as
> > > Linux and is already powered up and running by the bootloader.
> > >
> > > This patch adds a check using dev_pm_genpd_is_on() to verify whether the
> > > M-core's power domains are already on. If all power domain devices are
> > > on, the driver assumes the M-core is running and proceed to attach to
> > > it.
> > >
> > > To accomplish this, we need to avoid passing any attach_data or flags to
> > > dev_pm_domain_attach_list(), allowing the platform device become a
> > > consumer of the power domain provider without changing its current
> > > state.
> > >
> > > During probe, also enable and sync the device runtime PM 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>
> > > Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
> > > Reviewed-by: Peng Fan <peng.fan@nxp.com>
> > > Signed-off-by: Hiago De Franco <hiago.franco@toradex.com>
> > > ---
> > > v6 -> v7:
> > > - Added Peng reviewed-by.
> > > v5 -> v6:
> > > - Commit description improved, as suggested. Added Ulf Hansson reviewed
> > > by. Comment on imx-rproc.c improved.
> > > 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..24597b60c5b0 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 powered up and running when the kernel booted (e.g.,
> > > + * started by U-Boot's bootaux command). 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;
> > > + }
> > > + }
> >
> > I was doing one final review of this work when I noticed the return code for
> > dev_pm_domain_attach_list() is never checked for error.
>
> The for loop covers the error condition correctly, I think. It's only
> when ret >=1 when the loop should be started - and ret is propagated
> to the caller a few lines below.
>
> >
> > Thanks,
> > Mathieu
> >
>
> Kind regards
> Uffe
>
> > > +
> > > + 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
> > >

Best Regards,

Hiago.