linux-kernel - Re: [PATCH v7 3/5] remoteproc: Add support for runtime PM

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Message-Id: <P2TQAQ.3VDG3B8W2EPF3@crapouillou.net>
Date:   Fri, 22 May 2020 19:11:13 +0200
From:   Paul Cercueil <paul@...pouillou.net>
To:     Suman Anna <s-anna@...com>
Cc:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Ohad Ben-Cohen <ohad@...ery.com>,
        Arnaud Pouliquen <arnaud.pouliquen@...com>, od@...c.me,
        linux-remoteproc@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, Tero Kristo <t-kristo@...com>
Subject: Re: [PATCH v7 3/5] remoteproc: Add support for runtime PM

Hi Suman,

Le ven. 22 mai 2020 à 11:47, Suman Anna <s-anna@...com> a écrit :
> Hi Paul,
> 
> On 5/15/20 5:43 AM, Paul Cercueil wrote:
>> Call pm_runtime_get_sync() before the firmware is loaded, and
>> pm_runtime_put() after the remote processor has been stopped.
>> 
>> Even though the remoteproc device has no PM callbacks, this allows 
>> the
>> parent device's PM callbacks to be properly called.
> 
> I see this patch staged now for 5.8, and the latest -next branch has 
> broken the pm-runtime autosuspend feature we have in the OMAP 
> remoteproc driver. See commit 5f31b232c674 ("remoteproc/omap: Add 
> support for runtime auto-suspend/resume").
> 
> What was the original purpose of this patch, because there can be 
> differing backends across different SoCs.

Did you try pm_suspend_ignore_children()? It looks like it was made for 
your use-case.

Cheers,
-Paul

> 
> regards
> Suman
> 
>> 
>> Signed-off-by: Paul Cercueil <paul@...pouillou.net>
>> ---
>> 
>> Notes:
>>      v2-v4: No change
>>      v5: Move calls to prepare/unprepare to 
>> rproc_fw_boot/rproc_shutdown
>>      v6: Instead of prepare/unprepare callbacks, use PM runtime 
>> callbacks
>>      v7: Check return value of pm_runtime_get_sync()
>> 
>>   drivers/remoteproc/remoteproc_core.c | 17 ++++++++++++++++-
>>   1 file changed, 16 insertions(+), 1 deletion(-)
>> 
>> diff --git a/drivers/remoteproc/remoteproc_core.c 
>> b/drivers/remoteproc/remoteproc_core.c
>> index a7f96bc98406..e33d1ef27981 100644
>> --- a/drivers/remoteproc/remoteproc_core.c
>> +++ b/drivers/remoteproc/remoteproc_core.c
>> @@ -29,6 +29,7 @@
>>   #include <linux/devcoredump.h>
>>   #include <linux/rculist.h>
>>   #include <linux/remoteproc.h>
>> +#include <linux/pm_runtime.h>
>>   #include <linux/iommu.h>
>>   #include <linux/idr.h>
>>   #include <linux/elf.h>
>> @@ -1382,6 +1383,12 @@ static int rproc_fw_boot(struct rproc *rproc, 
>> const struct firmware *fw)
>>   	if (ret)
>>   		return ret;
>>   +	ret = pm_runtime_get_sync(dev);
>> +	if (ret < 0) {
>> +		dev_err(dev, "pm_runtime_get_sync failed: %d\n", ret);
>> +		return ret;
>> +	}
>> +
>>   	dev_info(dev, "Booting fw image %s, size %zd\n", name, fw->size);
>>     	/*
>> @@ -1391,7 +1398,7 @@ static int rproc_fw_boot(struct rproc *rproc, 
>> const struct firmware *fw)
>>   	ret = rproc_enable_iommu(rproc);
>>   	if (ret) {
>>   		dev_err(dev, "can't enable iommu: %d\n", ret);
>> -		return ret;
>> +		goto put_pm_runtime;
>>   	}
>>     	rproc->bootaddr = rproc_get_boot_addr(rproc, fw);
>> @@ -1435,6 +1442,8 @@ static int rproc_fw_boot(struct rproc *rproc, 
>> const struct firmware *fw)
>>   	rproc->table_ptr = NULL;
>>   disable_iommu:
>>   	rproc_disable_iommu(rproc);
>> +put_pm_runtime:
>> +	pm_runtime_put(dev);
>>   	return ret;
>>   }
>>   @@ -1840,6 +1849,8 @@ void rproc_shutdown(struct rproc *rproc)
>>     	rproc_disable_iommu(rproc);
>>   +	pm_runtime_put(dev);
>> +
>>   	/* Free the copy of the resource table */
>>   	kfree(rproc->cached_table);
>>   	rproc->cached_table = NULL;
>> @@ -2118,6 +2129,9 @@ struct rproc *rproc_alloc(struct device *dev, 
>> const char *name,
>>     	rproc->state = RPROC_OFFLINE;
>>   +	pm_runtime_no_callbacks(&rproc->dev);
>> +	pm_runtime_enable(&rproc->dev);
>> +
>>   	return rproc;
>>   }
>>   EXPORT_SYMBOL(rproc_alloc);
>> @@ -2133,6 +2147,7 @@ EXPORT_SYMBOL(rproc_alloc);
>>    */
>>   void rproc_free(struct rproc *rproc)
>>   {
>> +	pm_runtime_disable(&rproc->dev);
>>   	put_device(&rproc->dev);
>>   }
>>   EXPORT_SYMBOL(rproc_free);
>> 
>