linux-kernel - Re: [PATCH V4 2/2] remoteproc: support attach recovery after rproc crash

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Date:   Mon, 30 May 2022 11:50:51 -0600
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     "Peng Fan (OSS)" <peng.fan@....nxp.com>
Cc:     bjorn.andersson@...aro.org, arnaud.pouliquen@...s.st.com,
        linux-remoteproc@...r.kernel.org, linux-kernel@...r.kernel.org,
        peng.fan@....com
Subject: Re: [PATCH V4 2/2] remoteproc: support attach recovery after rproc
 crash

On Wed, Mar 23, 2022 at 11:44:05AM +0800, Peng Fan (OSS) wrote:
> From: Peng Fan <peng.fan@....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 attach recovery after crash and trigger watchdog
> reboot. It does not need main processor to load image, or stop/start M4
> core.
> 
> Introduce two functions: rproc_attach_recovery, rproc_firmware_recovery
> for the two cases. Firmware recovery is as before, let main processor to
> help recovery, while attach recovery is recover itself withou help.
> To attach recovery, we only do detach and attach.
> 
> Signed-off-by: Peng Fan <peng.fan@....com>
> ---
>  drivers/remoteproc/remoteproc_core.c | 67 ++++++++++++++++++++--------
>  1 file changed, 48 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index c510125769b9..ad04515750ef 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -1887,6 +1887,50 @@ static int __rproc_detach(struct rproc *rproc)
>  	return 0;
>  }
>  
> +static int rproc_attach_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);

The correct functions to call here are __rproc_detach() and __rproc_attach() -
they are similar to rproc_stop() and rproc_start() without the parts related to
the firmware image.

And you should not be dealing with rproc->power at this stage, which leaves the
remote processor's state machine in the same way as the start/stop scenario.  

That being said, now that we actually count how many instances are requesting
the remote processor to be powered, we might have a problem with rproc->power when
the system is recovered after a crash.  But we can address that when we get
there.

Thanks,
Mathieu

> +}
> +
> +static int rproc_firmware_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 +1945,6 @@ 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 +1958,10 @@ 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_has_feature(rproc, RPROC_FEAT_ATTACH_RECOVERY))
> +		ret = rproc_attach_recovery(rproc);
> +	else
> +		ret = rproc_firmware_recovery(rproc);
>  
>  unlock_mutex:
>  	mutex_unlock(&rproc->lock);
> -- 
> 2.25.1
>