diff mbox series

[v3,11/14] remoteproc: Deal with synchronisation when changing FW image

Message ID 20200424200135.28825-12-mathieu.poirier@linaro.org
State New
Headers show
Series remoteproc: Add support for synchronisaton with rproc | expand

Commit Message

Mathieu Poirier April 24, 2020, 8:01 p.m. UTC
This patch prevents the firmware image from being displayed or changed
when the remoteproc core is synchronising with a remote processor. This
is 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_sysfs.c | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

Comments

Arnaud POULIQUEN April 29, 2020, 8:52 a.m. UTC | #1
On 4/24/20 10:01 PM, Mathieu Poirier wrote:
> This patch prevents the firmware image from being displayed or changed
> when the remoteproc core is synchronising with a remote processor. This
> is 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_sysfs.c | 24 +++++++++++++++++++++++-
>  1 file changed, 23 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/remoteproc/remoteproc_sysfs.c b/drivers/remoteproc/remoteproc_sysfs.c
> index 7f8536b73295..cdd322a6ecfa 100644
> --- a/drivers/remoteproc/remoteproc_sysfs.c
> +++ b/drivers/remoteproc/remoteproc_sysfs.c
> @@ -13,9 +13,20 @@
>  static ssize_t firmware_show(struct device *dev, struct device_attribute *attr,
>  			  char *buf)
>  {
> +	ssize_t ret;
>  	struct rproc *rproc = to_rproc(dev);
>  
> -	return sprintf(buf, "%s\n", rproc->firmware);
> +	/*
> +	 * In most instances there is no guarantee about the firmware
> +	 * that was loaded by the external entity.  As such simply don't
> +	 * print anything.
> +	 */
> +	if (rproc_needs_syncing(rproc))
> +		ret = sprintf(buf, "\n");

A default name is provided in sysfs if no firmware is started/synchronised on boot.

IMO providing an empty name here could be confusing.
Perhaps a refactoring of this sysfs entry would be nice:
 - Normal boot (no firmware loaded) : empty name instead of a default name
 - auto_boot: name provided by the platform driver or default name ( current implementation)
 - synchronization: a predefined name such as Default, unknown, External, None,...   

> +	else
> +		ret = sprintf(buf, "%s\n", rproc->firmware);
> +
> +	return ret;
>  }
>  
>  /* Change firmware name via sysfs */
> @@ -39,6 +50,17 @@ static ssize_t firmware_store(struct device *dev,
>  		goto out;
>  	}
>  
> +	/*
> +	 * There is no point in trying to change the firmware if loading the
> +	 * image of the remote processor is done by another entity.
> +	 */
> +	if (rproc_needs_syncing(rproc)) {
> +		dev_err(dev,
> +			"can't change firmware while synchronising with MCU\n");

I don't know if you decide to keep "MCU" or not. If not the case
you have also some other instances in your patch 9/14.

Regards
Arnaud

> +		err = -EBUSY;
> +		goto out;
> +	}
> +
>  	len = strcspn(buf, "\n");
>  	if (!len) {
>  		dev_err(dev, "can't provide a NULL firmware\n");
>
Mathieu Poirier April 30, 2020, 8:32 p.m. UTC | #2
On Wed, Apr 29, 2020 at 10:52:48AM +0200, Arnaud POULIQUEN wrote:
> 
> 
> On 4/24/20 10:01 PM, Mathieu Poirier wrote:
> > This patch prevents the firmware image from being displayed or changed
> > when the remoteproc core is synchronising with a remote processor. This
> > is 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_sysfs.c | 24 +++++++++++++++++++++++-
> >  1 file changed, 23 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/remoteproc/remoteproc_sysfs.c b/drivers/remoteproc/remoteproc_sysfs.c
> > index 7f8536b73295..cdd322a6ecfa 100644
> > --- a/drivers/remoteproc/remoteproc_sysfs.c
> > +++ b/drivers/remoteproc/remoteproc_sysfs.c
> > @@ -13,9 +13,20 @@
> >  static ssize_t firmware_show(struct device *dev, struct device_attribute *attr,
> >  			  char *buf)
> >  {
> > +	ssize_t ret;
> >  	struct rproc *rproc = to_rproc(dev);
> >  
> > -	return sprintf(buf, "%s\n", rproc->firmware);
> > +	/*
> > +	 * In most instances there is no guarantee about the firmware
> > +	 * that was loaded by the external entity.  As such simply don't
> > +	 * print anything.
> > +	 */
> > +	if (rproc_needs_syncing(rproc))
> > +		ret = sprintf(buf, "\n");
> 
> A default name is provided in sysfs if no firmware is started/synchronised on boot.
> 
> IMO providing an empty name here could be confusing.
> Perhaps a refactoring of this sysfs entry would be nice:
>  - Normal boot (no firmware loaded) : empty name instead of a default name

That is guaranteed to break user space so we can't proceed this way.

>  - auto_boot: name provided by the platform driver or default name ( current implementation)
>  - synchronization: a predefined name such as Default, unknown, External, None,...   

Loic had the same comment.  Usually it is best to provide sysfs output that
don't need parsing, i.e 0/1 or nothing at all, but in the remoteproc subsystem
we already have "state", "name" and "firmware" that need parsing.  As such my
next revision will have "unknown", which I think is the best way to describe the
situation.

> 
> > +	else
> > +		ret = sprintf(buf, "%s\n", rproc->firmware);
> > +
> > +	return ret;
> >  }
> >  
> >  /* Change firmware name via sysfs */
> > @@ -39,6 +50,17 @@ static ssize_t firmware_store(struct device *dev,
> >  		goto out;
> >  	}
> >  
> > +	/*
> > +	 * There is no point in trying to change the firmware if loading the
> > +	 * image of the remote processor is done by another entity.
> > +	 */
> > +	if (rproc_needs_syncing(rproc)) {
> > +		dev_err(dev,
> > +			"can't change firmware while synchronising with MCU\n");
> 
> I don't know if you decide to keep "MCU" or not. If not the case
> you have also some other instances in your patch 9/14.

MCU should be long gone.  I thought I had spotted them all but was obviously
wrong.

> 
> Regards
> Arnaud
> 
> > +		err = -EBUSY;
> > +		goto out;
> > +	}
> > +
> >  	len = strcspn(buf, "\n");
> >  	if (!len) {
> >  		dev_err(dev, "can't provide a NULL firmware\n");
> >
Bjorn Andersson May 6, 2020, 1:27 a.m. UTC | #3
On Fri 24 Apr 13:01 PDT 2020, Mathieu Poirier wrote:

> This patch prevents the firmware image from being displayed or changed
> when the remoteproc core is synchronising with a remote processor. This
> is 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_sysfs.c | 24 +++++++++++++++++++++++-
>  1 file changed, 23 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/remoteproc/remoteproc_sysfs.c b/drivers/remoteproc/remoteproc_sysfs.c
> index 7f8536b73295..cdd322a6ecfa 100644
> --- a/drivers/remoteproc/remoteproc_sysfs.c
> +++ b/drivers/remoteproc/remoteproc_sysfs.c
> @@ -13,9 +13,20 @@
>  static ssize_t firmware_show(struct device *dev, struct device_attribute *attr,
>  			  char *buf)
>  {
> +	ssize_t ret;
>  	struct rproc *rproc = to_rproc(dev);
>  
> -	return sprintf(buf, "%s\n", rproc->firmware);
> +	/*
> +	 * In most instances there is no guarantee about the firmware
> +	 * that was loaded by the external entity.  As such simply don't
> +	 * print anything.

Not only "in most instances", we have no idea what firmware is running,
so this can be shortened.

However, this does implicate that on_init = true, after_crash = false,
this will read blank, but a future rproc_report_crash() will indeed load
and boot rproc->firmware.

> +	 */
> +	if (rproc_needs_syncing(rproc))
> +		ret = sprintf(buf, "\n");
> +	else
> +		ret = sprintf(buf, "%s\n", rproc->firmware);
> +
> +	return ret;
>  }
>  
>  /* Change firmware name via sysfs */
> @@ -39,6 +50,17 @@ static ssize_t firmware_store(struct device *dev,
>  		goto out;
>  	}
>  
> +	/*
> +	 * There is no point in trying to change the firmware if loading the
> +	 * image of the remote processor is done by another entity.
> +	 */
> +	if (rproc_needs_syncing(rproc)) {
> +		dev_err(dev,
> +			"can't change firmware while synchronising with MCU\n");

The conditional checks for a future event, but the error message
indicates an ongoing event. How about "can't change firmware on remote
controlled remote processor"? "externally controlled"?

Regards,
Bjorn

> +		err = -EBUSY;
> +		goto out;
> +	}
> +
>  	len = strcspn(buf, "\n");
>  	if (!len) {
>  		dev_err(dev, "can't provide a NULL firmware\n");
> -- 
> 2.20.1
>
diff mbox series

Patch

diff --git a/drivers/remoteproc/remoteproc_sysfs.c b/drivers/remoteproc/remoteproc_sysfs.c
index 7f8536b73295..cdd322a6ecfa 100644
--- a/drivers/remoteproc/remoteproc_sysfs.c
+++ b/drivers/remoteproc/remoteproc_sysfs.c
@@ -13,9 +13,20 @@ 
 static ssize_t firmware_show(struct device *dev, struct device_attribute *attr,
 			  char *buf)
 {
+	ssize_t ret;
 	struct rproc *rproc = to_rproc(dev);
 
-	return sprintf(buf, "%s\n", rproc->firmware);
+	/*
+	 * In most instances there is no guarantee about the firmware
+	 * that was loaded by the external entity.  As such simply don't
+	 * print anything.
+	 */
+	if (rproc_needs_syncing(rproc))
+		ret = sprintf(buf, "\n");
+	else
+		ret = sprintf(buf, "%s\n", rproc->firmware);
+
+	return ret;
 }
 
 /* Change firmware name via sysfs */
@@ -39,6 +50,17 @@  static ssize_t firmware_store(struct device *dev,
 		goto out;
 	}
 
+	/*
+	 * There is no point in trying to change the firmware if loading the
+	 * image of the remote processor is done by another entity.
+	 */
+	if (rproc_needs_syncing(rproc)) {
+		dev_err(dev,
+			"can't change firmware while synchronising with MCU\n");
+		err = -EBUSY;
+		goto out;
+	}
+
 	len = strcspn(buf, "\n");
 	if (!len) {
 		dev_err(dev, "can't provide a NULL firmware\n");