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Date:   Tue, 18 Jan 2022 11:44:53 -0700
From:   Mathieu Poirier <mathieu.poirier@linaro.org>
To:     "Peng Fan (OSS)" <peng.fan@oss.nxp.com>
Cc:     bjorn.andersson@linaro.org, shawnguo@kernel.org,
        s.hauer@pengutronix.de, kernel@pengutronix.de, festevam@gmail.com,
        linux-imx@nxp.com, linux-remoteproc@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Peng Fan <peng.fan@nxp.com>
Subject: Re: [PATCH 3/9] remoteproc: support self recovery after rproc crash
Message-ID: <20220118184453.GE1119324@p14s>
References: <20220111033333.403448-1-peng.fan@oss.nxp.com>
 <20220111033333.403448-6-peng.fan@oss.nxp.com>
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On Tue, Jan 11, 2022 at 11:33:27AM +0800, Peng Fan (OSS) wrote:
> From: Peng Fan <peng.fan@nxp.com>
> 
> Current logic only support main processor to stop/start the remote
> processor after rproc crash. However to SoC, such as i.MX8QM/QXP, the
> remote processor could do self recovery after crash and trigger watchdog
> reboot. It does not need main processor to load image, stop/start M4
> core.
> 
> This patch add a new flag to indicate whether the SoC has self recovery
> capability. And introduce two functions: rproc_self_recovery,
> rproc_assisted_recovery for the two cases. Assisted recovery is as
> before, let main processor to help recovery, while self recovery is
> recover itself withou help. To self recovery, we only do detach and
> attach.
> 
> Signed-off-by: Peng Fan <peng.fan@nxp.com>
> ---
>  drivers/remoteproc/remoteproc_core.c | 66 ++++++++++++++++++++--------
>  include/linux/remoteproc.h           |  2 +
>  2 files changed, 49 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index 69f51acf235e..4bd5544dab8f 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -1887,6 +1887,49 @@ static int __rproc_detach(struct rproc *rproc)
>  	return 0;
>  }
>  
> +static int rproc_self_recovery(struct rproc *rproc)
> +{
> +	int ret;
> +
> +	mutex_unlock(&rproc->lock);
> +	ret = rproc_detach(rproc);
> +	mutex_lock(&rproc->lock);
> +	if (ret)
> +		return ret;
> +
> +	if (atomic_inc_return(&rproc->power) > 1)
> +		return 0;
> +	return rproc_attach(rproc);
> +}
> +
> +static int rproc_assisted_recovery(struct rproc *rproc)
> +{
> +	const struct firmware *firmware_p;
> +	struct device *dev = &rproc->dev;
> +	int ret;
> +
> +	ret = rproc_stop(rproc, true);
> +	if (ret)
> +		return ret;
> +
> +	/* generate coredump */
> +	rproc->ops->coredump(rproc);
> +
> +	/* load firmware */
> +	ret = request_firmware(&firmware_p, rproc->firmware, dev);
> +	if (ret < 0) {
> +		dev_err(dev, "request_firmware failed: %d\n", ret);
> +		return ret;
> +	}
> +
> +	/* boot the remote processor up again */
> +	ret = rproc_start(rproc, firmware_p);
> +
> +	release_firmware(firmware_p);
> +
> +	return ret;
> +}
> +
>  /**
>   * rproc_trigger_recovery() - recover a remoteproc
>   * @rproc: the remote processor
> @@ -1901,7 +1944,6 @@ static int __rproc_detach(struct rproc *rproc)
>   */
>  int rproc_trigger_recovery(struct rproc *rproc)
>  {
> -	const struct firmware *firmware_p;
>  	struct device *dev = &rproc->dev;
>  	int ret;
>  
> @@ -1915,24 +1957,10 @@ int rproc_trigger_recovery(struct rproc *rproc)
>  
>  	dev_err(dev, "recovering %s\n", rproc->name);
>  
> -	ret = rproc_stop(rproc, true);
> -	if (ret)
> -		goto unlock_mutex;
> -
> -	/* generate coredump */
> -	rproc->ops->coredump(rproc);
> -
> -	/* load firmware */
> -	ret = request_firmware(&firmware_p, rproc->firmware, dev);
> -	if (ret < 0) {
> -		dev_err(dev, "request_firmware failed: %d\n", ret);
> -		goto unlock_mutex;
> -	}
> -
> -	/* boot the remote processor up again */
> -	ret = rproc_start(rproc, firmware_p);
> -
> -	release_firmware(firmware_p);
> +	if (rproc->self_recovery)
> +		ret = rproc_self_recovery(rproc);
> +	else
> +		ret = rproc_assisted_recovery(rproc);

The problem of how to handle crash recoveries for processors that have been
attached to is difficult.  Finding a solution for that should be on a patchset
of its own so that people can provide input.

>  
>  unlock_mutex:
>  	mutex_unlock(&rproc->lock);
> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> index e0600e1e5c17..b32ef46f8aa4 100644
> --- a/include/linux/remoteproc.h
> +++ b/include/linux/remoteproc.h
> @@ -529,6 +529,7 @@ struct rproc_dump_segment {
>   * @elf_machine: firmware ELF machine
>   * @cdev: character device of the rproc
>   * @cdev_put_on_release: flag to indicate if remoteproc should be shutdown on @char_dev release
> + * @self_recovery: flag to indicate if remoteproc support self recovery
>   */
>  struct rproc {
>  	struct list_head node;
> @@ -568,6 +569,7 @@ struct rproc {
>  	u16 elf_machine;
>  	struct cdev cdev;
>  	bool cdev_put_on_release;
> +	bool self_recovery;
>  };
>  
>  /**
> -- 
> 2.25.1
>