Re: [PATCH] rcar-vin: Use of_nodes as specified by the subdev

Simon Horman
2017-04-26T09:14:06Z

On Wed, Apr 26, 2017 at 11:00:30AM +0200, Niklas Söderlund wrote:
> Hi Simon,
>
> Thanks for your feedback.
>
> On 2017-04-26 09:23:20 +0200, Simon Horman wrote:
> > Hi Kieran,
> >
> > On Tue, Apr 25, 2017 at 03:55:00PM +0100, Kieran Bingham wrote:
> > > From: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
> > >
> > > The rvin_digital_notify_bound() call dereferences the subdev->dev
> > > pointer to obtain the of_node. On some error paths, this dev node can be
> > > set as NULL. The of_node is mapped into the subdevice structure on
> > > initialisation, so this is a safer source to compare the nodes.
> > >
> > > Dereference the of_node from the subdev structure instead of the dev
> > > structure.
> > >
> > > Fixes: 83fba2c06f19 ("rcar-vin: rework how subdevice is found and
> > > bound")
> > > Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
> > > ---
> > > drivers/media/platform/rcar-vin/rcar-core.c | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/media/platform/rcar-vin/rcar-core.c b/drivers/media/platform/rcar-vin/rcar-core.c
> > > index 5861ab281150..a530dc388b95 100644
> > > --- a/drivers/media/platform/rcar-vin/rcar-core.c
> > > +++ b/drivers/media/platform/rcar-vin/rcar-core.c
> > > @@ -469,7 +469,7 @@ static int rvin_digital_notify_bound(struct v4l2_async_notifier *notifier,
> > >
> > > v4l2_set_subdev_hostdata(subdev, vin);
> > >
> > > - if (vin->digital.asd.match.of.node == subdev->dev->of_node) {
> > > + if (vin->digital.asd.match.of.node == subdev->of_node) {
> > > /* Find surce and sink pad of remote subdevice */
> > >
> > > ret = rvin_find_pad(subdev, MEDIA_PAD_FL_SOURCE);
> >
> > I see two different accesses to subdev->dev->of_node in the version of
> > rcar-core.c in linux-next. So I'm unsure if the following comment makes
> > sense in the context of the version you are working on. It is that
> > I wonder if all accesses to subdev->dev->of_node should be updated.
>
> Are you sure you checked linux-next and not renesas-drivers? I checked
> next-20170424.
>
> $ git grep "dev->of_node" -- drivers/media/platform/rcar-vin/
> drivers/media/platform/rcar-vin/rcar-core.c:107: if (vin->digital.asd.match.of.node == subdev->dev->of_node) {
> drivers/media/platform/rcar-vin/rcar-core.c:161: ep = of_graph_get_endpoint_by_regs(vin->dev->of_node, 0, 0);
>
> Here vin->dev->of_node is correct and subdev->dev->of_node should be
> fixed by Kieran patch. I'm only asking to be sure I did not miss
> anything. In renesas-drivers the Gen3 patches are included and more
> references to subdev->dev->of_node exists, but as Kieran sates these
> fixes will be squashed into those patches since they are not yet picked
> up.

I think we are seeing the same thing, sorry for the noise.

git show next-20170424:drivers/media/platform/rcar-vin/rcar-core.c | grep -A 3 "dev->of_node"
if (vin->digital.asd.match.of.node == subdev->dev->of_node) {
vin_dbg(vin, "bound digital subdev %s\n", subdev->name);
vin->digital.subdev = subdev;
return 0;
--
ep = of_graph_get_endpoint_by_regs(vin->dev->of_node, 0, 0);
if (!ep)
return 0;