On Fri, Mar 27, 2020 at 01:50:18PM +0000, Loic PALLARDY wrote:
>
>
> > -----Original Message-----
> > From: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
> > Sent: mardi 24 mars 2020 22:46
> > To: bjorn.andersson@xxxxxxxxxx
> > Cc: ohad@xxxxxxxxxx; Loic PALLARDY <loic.pallardy@xxxxxx>; s-
> > anna@xxxxxx; peng.fan@xxxxxxx; Arnaud POULIQUEN
> > <arnaud.pouliquen@xxxxxx>; Fabien DESSENNE
> > <fabien.dessenne@xxxxxx>; linux-remoteproc@xxxxxxxxxxxxxxx
> > Subject: [PATCH v2 15/17] remoteproc: Correctly deal with MCU
> > synchronisation when changing FW image
> >
> > This patch prevents the firmware image from being displayed or changed
> > when
> > the remoteproc core is synchronising with an MCU. 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@xxxxxxxxxx>
> > ---
> > drivers/remoteproc/remoteproc_sysfs.c | 25
> > ++++++++++++++++++++++++-
> > 1 file changed, 24 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/remoteproc/remoteproc_sysfs.c
> > b/drivers/remoteproc/remoteproc_sysfs.c
> > index 7f8536b73295..4956577ad4b4 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_sync_with_mcu(rproc))
> > + ret = sprintf(buf, "\n");
> Is it enough to provide empty name, or should we add a message to indicate that's name is unkown/undefined ?
>
Don't know... It is easy to find plenty of cases in sysfs where null values are
represented with a "\n", and just as many where "unknown", "undefined" or "-1"
are used. I know GKH prefers the least amount of information as possible, hence
going with a "\n".
Again, no strong opinion...
> Regards,
> Loic
> > + else
> > + ret = sprintf(buf, "%s\n", rproc->firmware);
> > +
> > + return ret;
> > }
> >
> > /* Change firmware name via sysfs */
> > @@ -33,6 +44,18 @@ static ssize_t firmware_store(struct device *dev,
> > return -EINVAL;
> > }
> >
> > + /*
> > + * There is no point in trying to change the firmware if the MCU
> > + * is currently running or if loading of the image is done by
> > + * another entity.
> > + */
> > + if (rproc_sync_with_mcu(rproc)) {
> > + dev_err(dev,
> > + "can't change firmware while synchronising with
> > MCU\n");
> > + err = -EBUSY;
> > + goto out;
> > + }
> > +
> > if (rproc->state != RPROC_OFFLINE) {
> > dev_err(dev, "can't change firmware while running\n");
> > err = -EBUSY;
> > --
> > 2.20.1
>
