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

Arnaud POULIQUEN
2020-04-29T08:53:58Z

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");
>