Re: [PATCH v4 9/9] remoteproc: Properly handle firmware name when attaching

From: Arnaud POULIQUEN <arnaud.pouliquen@st.com>
To: Mathieu Poirier <mathieu.poirier@linaro.org>,
	"bjorn.andersson@linaro.org" <bjorn.andersson@linaro.org>,
	"ohad@wizery.com" <ohad@wizery.com>
Cc: "linux-remoteproc@vger.kernel.org"
	<linux-remoteproc@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Loic PALLARDY <loic.pallardy@st.com>,
	"s-anna@ti.com" <s-anna@ti.com>
Subject: Re: [PATCH v4 9/9] remoteproc: Properly handle firmware name when attaching
Date: Thu, 4 Jun 2020 16:16:42 +0200	[thread overview]
Message-ID: <1ddccc88-cde8-91ca-ee17-5fa5955ca80b@st.com> (raw)
In-Reply-To: <20200601175139.22097-10-mathieu.poirier@linaro.org>

Hi Mathieu,

On 6/1/20 7:51 PM, Mathieu Poirier wrote:
> This patch prevents the firmware image name from being displayed when
> the remoteproc core is attaching to a remote processor. This is needed
> needed since there is no guarantee about the nature of the firmware
> image that is loaded by the external entity.
> 
> Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
> ---
>  drivers/remoteproc/remoteproc_core.c  | 18 ++++++++++++++++++
>  drivers/remoteproc/remoteproc_sysfs.c | 16 ++++++++++++++--
>  include/linux/remoteproc.h            |  2 ++
>  3 files changed, 34 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index 0e23284fbd25..a8adc712e7f6 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -1642,6 +1642,14 @@ static int rproc_stop(struct rproc *rproc, bool crashed)
>  
>  	rproc->state = RPROC_OFFLINE;
>  
> +	/*
> +	 * The remote processor has been stopped and is now offline, which means
> +	 * that the next time it is brought back online the remoteproc core will
> +	 * be responsible to load its firmware.  As such it is no longer
> +	 * autonomous.
> +	 */
> +	rproc->autonomous = false;
> +
>  	dev_info(dev, "stopped remote processor %s\n", rproc->name);
>  
>  	return 0;
> @@ -2166,6 +2174,16 @@ int rproc_add(struct rproc *rproc)
>  	/* create debugfs entries */
>  	rproc_create_debug_dir(rproc);
>  
> +	/*
> +	 * Remind ourselves the remote processor has been attached to rather
> +	 * than booted by the remoteproc core.  This is important because the
> +	 * RPROC_DETACHED state will be lost as soon as the remote processor
> +	 * has been attached to.  Used in firmware_show() and reset in
> +	 * rproc_stop().
> +	 */
> +	if (rproc->state == RPROC_DETACHED)
> +		rproc->autonomous = true;
> +
>  	/* if rproc is marked always-on, request it to boot */
>  	if (rproc->auto_boot) {
>  		ret = rproc_trigger_auto_boot(rproc);
> diff --git a/drivers/remoteproc/remoteproc_sysfs.c b/drivers/remoteproc/remoteproc_sysfs.c
> index 8b462c501465..4ee158431f67 100644
> --- a/drivers/remoteproc/remoteproc_sysfs.c
> +++ b/drivers/remoteproc/remoteproc_sysfs.c
> @@ -14,8 +14,20 @@ static ssize_t firmware_show(struct device *dev, struct device_attribute *attr,
>  			  char *buf)
>  {
>  	struct rproc *rproc = to_rproc(dev);
> -
> -	return sprintf(buf, "%s\n", rproc->firmware);
> +	const char *firmware = rproc->firmware;
> +
> +	/*
> +	 * If the remote processor has been started by an external
> +	 * entity we have no idea of what image it is running.  As such
> +	 * simply display a generic string rather then rproc->firmware.
> +	 *
> +	 * Here we rely on the autonomous flag because a remote processor
> +	 * may have been attached to and currently in a running state.
> +	 */
> +	if (rproc->autonomous)
> +		firmware = "unknown";
> +
> +	return sprintf(buf, "%s\n", firmware);
>  }
>  
>  /* Change firmware name via sysfs */
> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> index bf6a310ba870..cf5e31556780 100644
> --- a/include/linux/remoteproc.h
> +++ b/include/linux/remoteproc.h
> @@ -491,6 +491,7 @@ struct rproc_dump_segment {
>   * @table_sz: size of @cached_table
>   * @has_iommu: flag to indicate if remote processor is behind an MMU
>   * @auto_boot: flag to indicate if remote processor should be auto-started
> + * @autonomous: true if an external entity has booted the remote processor
>   * @dump_segments: list of segments in the firmware
>   * @nb_vdev: number of vdev currently handled by rproc
>   */
> @@ -524,6 +525,7 @@ struct rproc {
>  	size_t table_sz;
>  	bool has_iommu;
>  	bool auto_boot;
> +	bool autonomous;

Do you need to define a new field? what about using rproc->firmware value?

In this case the platform driver could provide a name using rproc_alloc
even if in attached mode, for instance to identify a firmware version...

Regards,
Arnaud

>  	struct list_head dump_segments;
>  	int nb_vdev;
>  	u8 elf_class;
> 