Re: [PATCH 2/4] remoteproc: k3-r5: Introduce PM suspend/resume handlers

[Richard GENOUD <richard.genoud@xxxxxxxxxxx>]

Le 28/06/2024 à 22:48, Mathieu Poirier a écrit :
> On Fri, Jun 21, 2024 at 05:00:56PM +0200, Richard Genoud wrote:
> > This patch adds the support for system suspend/resume to the ti_k3_R5
> > remoteproc driver.
> >
> > In order to save maximum power, the approach here is to shutdown
> > completely the cores that were started by the kernel (i.e. those in
> > RUNNING state).
> > Those which were started before the kernel (in attached mode) will be
> > detached.
> >
> > The pm_notifier mechanism is used here because the remote procs firmwares
> > have to be reloaded at resume, and thus the driver must have access to
> > the file system were the firmware is stored.
> >
> > On suspend, the running remote procs are stopped, the attached remote
> > procs are detached and processor control released.
> >
> > On resume, the reverse operation is done.
> >
> > Based on work from: Hari Nagalla <hnagalla@xxxxxx>
> >
> > Signed-off-by: Richard Genoud <richard.genoud@xxxxxxxxxxx>
> > ---
> >   drivers/remoteproc/ti_k3_r5_remoteproc.c | 123 ++++++++++++++++++++++-
> >   1 file changed, 121 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/remoteproc/ti_k3_r5_remoteproc.c b/drivers/remoteproc/ti_k3_r5_remoteproc.c
> > index 39a47540c590..1f18b08618c8 100644
> > --- a/drivers/remoteproc/ti_k3_r5_remoteproc.c
> > +++ b/drivers/remoteproc/ti_k3_r5_remoteproc.c
> > @@ -20,6 +20,7 @@
> >   #include <linux/platform_device.h>
> >   #include <linux/pm_runtime.h>
> >   #include <linux/remoteproc.h>
> > +#include <linux/suspend.h>
> >   #include <linux/reset.h>
> >   #include <linux/slab.h>
> >   
> > @@ -112,6 +113,7 @@ struct k3_r5_cluster {
> >   	struct list_head cores;
> >   	wait_queue_head_t core_transition;
> >   	const struct k3_r5_soc_data *soc_data;
> > +	struct notifier_block pm_notifier;
> >   };
> >   
> >   /**
> > @@ -577,7 +579,8 @@ static int k3_r5_rproc_start(struct rproc *rproc)
> >   		/* do not allow core 1 to start before core 0 */
> >   		core0 = list_first_entry(&cluster->cores, struct k3_r5_core,
> >   					 elem);
> > -		if (core != core0 && core0->rproc->state == RPROC_OFFLINE) {
> > +		if (core != core0 && (core0->rproc->state == RPROC_OFFLINE ||
> > +				      core0->rproc->state == RPROC_SUSPENDED)) {
>
> If I understand correctly, this is to address a possible race condition between
> user space wanting to start core1 via sysfs while the system is being suspended.
> Is this correct?  If so, please add a comment to explain what is going on.
> Otherwise a comment is obviously needed.
Yes, you're right, I'll add a comment on the race condition at suspend.

> >   			dev_err(dev, "%s: can not start core 1 before core 0\n",
> >   				__func__);
> >   			ret = -EPERM;
> > @@ -646,7 +649,8 @@ static int k3_r5_rproc_stop(struct rproc *rproc)
> >   		/* do not allow core 0 to stop before core 1 */
> >   		core1 = list_last_entry(&cluster->cores, struct k3_r5_core,
> >   					elem);
> > -		if (core != core1 && core1->rproc->state != RPROC_OFFLINE) {
> > +		if (core != core1 && core1->rproc->state != RPROC_OFFLINE &&
> > +		    core1->rproc->state != RPROC_SUSPENDED) {
> >   			dev_err(dev, "%s: can not stop core 0 before core 1\n",
> >   				__func__);
> >   			ret = -EPERM;
> > @@ -1238,6 +1242,117 @@ static int k3_r5_rproc_configure_mode(struct k3_r5_rproc *kproc)
> >   	return ret;
> >   }
> >   
> > +static int k3_r5_rproc_suspend(struct k3_r5_rproc *kproc)
> > +{
> > +	unsigned int rproc_state = kproc->rproc->state;
> > +	int ret;
> > +
> > +	if (rproc_state != RPROC_RUNNING && rproc_state != RPROC_ATTACHED)
> > +		return 0;
> > +
> > +	if (rproc_state == RPROC_RUNNING)
> > +		ret = rproc_shutdown(kproc->rproc);
> > +	else
> > +		ret = rproc_detach(kproc->rproc);
> > +
> > +	if (ret) {
> > +		dev_err(kproc->dev, "Failed to %s rproc (%d)\n",
> > +			(rproc_state == RPROC_RUNNING) ? "shutdown" : "detach",
> > +			ret);
> > +		return ret;
> > +	}
> > +
> > +	kproc->rproc->state = RPROC_SUSPENDED;
> > +
> > +	return ret;
> > +}
> > +
> > +static int k3_r5_rproc_resume(struct k3_r5_rproc *kproc)
> > +{
> > +	int ret;
> > +
> > +	if (kproc->rproc->state != RPROC_SUSPENDED)
> > +		return 0;
> > +
> > +	ret = k3_r5_rproc_configure_mode(kproc);
> > +	if (ret < 0)
> > +		return -EBUSY;
> > +
> > +	/*
> > +	 * ret > 0 for IPC-only mode
> > +	 * ret == 0 for remote proc mode
> > +	 */
> > +	if (ret == 0) {
> > +		/*
> > +		 * remote proc looses its configuration when powered off.
> > +		 * So, we have to configure it again on resume.
> > +		 */
> > +		ret = k3_r5_rproc_configure(kproc);
> > +		if (ret < 0) {
> > +			dev_err(kproc->dev, "k3_r5_rproc_configure failed (%d)\n", ret);
> > +			return -EBUSY;
> > +		}
> > +	}
> > +
> > +	return rproc_boot(kproc->rproc);
> > +}
> > +
> > +static int k3_r5_cluster_pm_notifier_call(struct notifier_block *bl,
> > +					  unsigned long state, void *unused)
> > +{
> > +	struct k3_r5_cluster *cluster = container_of(bl, struct k3_r5_cluster,
> > +						     pm_notifier);
> > +	struct k3_r5_core *core;
> > +	int ret;
> > +
> > +	switch (state) {
> > +	case PM_HIBERNATION_PREPARE:
> > +	case PM_RESTORE_PREPARE:
> > +	case PM_SUSPEND_PREPARE:
> > +		/* core1 should be suspended before core0 */
> > +		list_for_each_entry_reverse(core, &cluster->cores, elem) {
> > +			/*
> > +			 * In LOCKSTEP mode, rproc is allocated only for
> > +			 * core0
> > +			 */
> > +			if (core->rproc) {
> > +				ret = k3_r5_rproc_suspend(core->rproc->priv);
> > +				if (ret)
> > +					dev_warn(core->dev,
> > +						 "k3_r5_rproc_suspend failed (%d)\n", ret);
> > +			}
> > +
> > +			ret = ti_sci_proc_release(core->tsp);
> > +			if (ret)
> > +				dev_warn(core->dev, "ti_sci_proc_release failed (%d)\n", ret);
> > +		}
> > +		break;
> > +	case PM_POST_HIBERNATION:
> > +	case PM_POST_RESTORE:
> > +	case PM_POST_SUSPEND:
> > +		/* core0 should be started before core1 */
> > +		list_for_each_entry(core, &cluster->cores, elem) {
> > +			ret = ti_sci_proc_request(core->tsp);
> > +			if (ret)
> > +				dev_warn(core->dev, "ti_sci_proc_request failed (%d)\n", ret);
> > +
> > +			/*
> > +			 * In LOCKSTEP mode, rproc is allocated only for
> > +			 * core0
> > +			 */
> > +			if (core->rproc) {
> > +				ret = k3_r5_rproc_resume(core->rproc->priv);
> > +				if (ret)
> > +					dev_warn(core->dev,
> > +						 "k3_r5_rproc_resume failed (%d)\n", ret);
> > +			}
> > +		}
> > +		break;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> >   static int k3_r5_cluster_rproc_init(struct platform_device *pdev)
> >   {
> >   	struct k3_r5_cluster *cluster = platform_get_drvdata(pdev);
> > @@ -1336,6 +1451,9 @@ static int k3_r5_cluster_rproc_init(struct platform_device *pdev)
> >   		}
> >   	}
> >   
> > +	cluster->pm_notifier.notifier_call = k3_r5_cluster_pm_notifier_call;
> > +	register_pm_notifier(&cluster->pm_notifier);
> > +
> >   	return 0;
> >   
> >   err_split:
> > @@ -1402,6 +1520,7 @@ static void k3_r5_cluster_rproc_exit(void *data)
> >   		rproc_free(rproc);
> >   		core->rproc = NULL;
> >   	}
> > +	unregister_pm_notifier(&cluster->pm_notifier);
> >   }
> >   
> >   static int k3_r5_core_of_get_internal_memories(struct platform_device *pdev,

Thanks !