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

Bjorn Andersson
2020-05-06T01:27:07Z

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
>