Re: [PATCH v2 3/4] media: v4l2-async: Log message in case of heterogenous fwnode match

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Geert,

On Wed, Mar 18, 2020 at 10:16:37AM +0100, Geert Uytterhoeven wrote:
> On Wed, Mar 18, 2020 at 1:26 AM Laurent Pinchart wrote:
> > When a notifier supplies a device fwnode and a subdev supplies an
> > endpoint fwnode, incorrect matches may occur if multiple subdevs
> > correspond to the same device fwnode. This can't be handled
> > transparently in the framework, and requires the notifier to switch to
> > endpoint fwnodes. Log a message to notify of this problem. A second
> > message is added to help accelerating the transition to endpoint
> > matching.
> >
> > Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> 
> Thanks for your patch!
> 
> > --- a/drivers/media/v4l2-core/v4l2-async.c
> > +++ b/drivers/media/v4l2-core/v4l2-async.c
> > @@ -113,7 +114,28 @@ static bool match_fwnode(struct v4l2_async_notifier *notifier,
> >
> >         fwnode_handle_put(dev_fwnode);
> >
> > -       return dev_fwnode == other_fwnode;
> > +       if (dev_fwnode != other_fwnode)
> > +               return false;
> > +
> > +       /*
> > +        * We have an heterogenous match. Retrieve the struct device of the
> > +        * side that matched on a device fwnode to print its driver name.
> > +        */
> > +       if (sd_fwnode_is_ep)
> > +               dev = notifier->v4l2_dev ? notifier->v4l2_dev->dev
> > +                   : notifier->sd->dev;
> > +       else
> > +               dev = sd->dev;
> > +
> > +       if (dev && dev->driver) {
> > +               if (sd_fwnode_is_ep)
> > +                       dev_info(dev, "Driver %s uses device fwnode, incorrect match may occur\n",
> > +                                dev->driver->name);
> 
> I think that deserves a dev_warn().
> 
> > +               dev_info(dev, "Consider updating driver %s to match on endpoints\n",
> > +                        dev->driver->name);
> 
> And dev_notice(), while at it ;-)

A rarely used, but totally appropriate level. I'll fix both.

> > +       }
> > +
> > +       return true;
> >  }

-- 
Regards,

Laurent Pinchart