On Wed, Nov 23, 2016 at 05:10:42PM +0200, Sakari Ailus wrote:

Hi Javi,

Hi Sakari,

On Wed, Nov 23, 2016 at 10:09:57AM +0000, Javi Merino wrote:

quoted

In asd's configured with V4L2_ASYNC_MATCH_OF, if the v4l2 subdev is in
a devicetree overlay, its of_node pointer will be different each time
the overlay is applied.  We are not interested in matching the
pointer, what we want to match is that the path is the one we are
expecting.  Change to use of_node_cmp() so that we continue matching
after the overlay has been removed and reapplied.

Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Javier Martinez Canillas <redacted>
Cc: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Javi Merino <javi.merino@kernel.org>
---
Hi,

I feel it is a bit of a hack, but I couldn't think of anything better.
I'm ccing devicetree@ and Pantelis because there may be a simpler
solution.

First I have to admit that I'm not an expert when it comes to DT overlays.

That said, my understanding is that the sub-device and the async sub-device
are supposed to point to the exactly same DT node. I wonder if there's
actually anything wrong in the current code.

If the overlay has changed between probing the driver for the async notifier
and the async sub-device, there should be no match here, should there? The
two nodes actually point to a node in a different overlay in that case.

Overlays are parts of the devicetree that can be added and removed.
When the overlay is applied, the camera driver is probed and does
v4l2_async_register_subdev().  However, v4l2_async_belongs() fails.
The problem is with comparing pointers.  I haven't looked at the
implementation of overlays in detail, but what I see is that the
of_node pointer changes when you remove and reapply an overlay (I
guess it's dynamically allocated and when you remove the overlay, it's
freed).

Cheers,
Javi

quoted

 drivers/media/v4l2-core/v4l2-async.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/media/v4l2-core/v4l2-async.c b/drivers/media/v4l2-core/v4l2-async.c
index 5bada20..d33a17c 100644
--- a/drivers/media/v4l2-core/v4l2-async.c
+++ b/drivers/media/v4l2-core/v4l2-async.c

@@ -42,7 +42,8 @@ static bool match_devname(struct v4l2_subdev *sd,
 
 static bool match_of(struct v4l2_subdev *sd, struct v4l2_async_subdev *asd)
 {
-	return sd->of_node == asd->match.of.node;
+	return !of_node_cmp(of_node_full_name(sd->of_node),
+			    of_node_full_name(asd->match.of.node));
 }
 
 static bool match_custom(struct v4l2_subdev *sd, struct v4l2_async_subdev *asd)

-- 
Kind regards,

Sakari Ailus
e-mail: sakari.ailus@iki.fi	XMPP: sailus@retiisi.org.uk