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Message-ID: <ec73b430-1d63-4c77-8420-170c7727d454@bootlin.com>
Date: Mon, 1 Jul 2024 09:30:14 +0200
From: Richard GENOUD <richard.genoud@...tlin.com>
To: Mathieu Poirier <mathieu.poirier@...aro.org>
Cc: Bjorn Andersson <andersson@...nel.org>,
 Philipp Zabel <p.zabel@...gutronix.de>, Suman Anna <s-anna@...com>,
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
 Alexandre Belloni <alexandre.belloni@...tlin.com>,
 Udit Kumar <u-kumar1@...com>, Thomas Richard <thomas.richard@...tlin.com>,
 Gregory CLEMENT <gregory.clement@...tlin.com>, Hari Nagalla
 <hnagalla@...com>, Théo Lebrun <theo.lebrun@...tlin.com>,
 linux-remoteproc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] remoteproc: k3-r5: Introduce PM suspend/resume
 handlers

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@...com>
>>
>> Signed-off-by: Richard Genoud <richard.genoud@...tlin.com>
>> ---
>>   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 !


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