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

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Date:   Fri, 22 May 2020 11:47:34 -0500
From:   Suman Anna <s-anna@...com>
To:     Paul Cercueil <paul@...pouillou.net>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Ohad Ben-Cohen <ohad@...ery.com>,
        Arnaud Pouliquen <arnaud.pouliquen@...com>
CC:     <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 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.

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);
>