Re: [RESEND PATCH v3 02/17] media: v4l2-fwnode: Pass notifier to v4l2_async_register_fwnode_subdev()

[Steve Longerbeam]

Hi Sakari,

On 2/25/20 7:07 AM, Sakari Ailus wrote:
> Hi Steve,
>
> On Sat, Feb 15, 2020 at 11:41:21AM -0800, Steve Longerbeam wrote:
> > Instead of allocating a notifier in v4l2_async_register_fwnode_subdev(),
> > have the caller provide one. This allows the caller to implement
> > notifier ops (bind, unbind).
> >
> > The caller is now responsible for first initializing its notifier with a
> > call to v4l2_async_notifier_init().
> >
> > Signed-off-by: Steve Longerbeam <slongerbeam@xxxxxxxxx>
> Instead of improving v4l2_async_register_fwnode_subdev(), could you convert
> the users (IMX driver in this case) to call the preferred APIs instead? As
> the lines below show, v4l2_async_register_fwnode_subdev() has only two
> users left --- the other one of which is the IMX driver. After converting
> these two, we could just remove this API.
>
> See e.g. drivers/media/pci/intel/ipu3/ipu3-cio2.c and
> drivers/media/platform/omap3isp/isp.c for examples.

Shouldn't v4l2_async_notifier_add_fwnode_remote_subdev() check for the 
availability of the remote before adding it to the notifier's asd list, 
as in:

diff --git a/drivers/media/v4l2-core/v4l2-async.c 
b/drivers/media/v4l2-core/v4l2-async.c
index 8bde33c21ce4..b48ed68c6c6c 100644
--- a/drivers/media/v4l2-core/v4l2-async.c
+++ b/drivers/media/v4l2-core/v4l2-async.c
@@ -615,7 +615,7 @@ v4l2_async_notifier_add_fwnode_remote_subdev(struct 
v4l2_async_notifier *notif,
ÂÂÂÂÂÂÂ int ret;

ÂÂÂÂÂÂÂ remote = fwnode_graph_get_remote_port_parent(endpoint);
-ÂÂÂÂÂÂ if (!remote)
+ÂÂÂÂÂÂ if (!remote || !fwnode_device_is_available(remote))
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ return -ENOTCONN;

ÂÂÂÂÂÂÂ asd->match_type = V4L2_ASYNC_MATCH_FWNODE;


Otherwise we are back to the problem that the notifier will never 
complete because the remote's driver is not probed.

Steve

> > ---
> > Changes in v3:
> > - added the missing calls to unregister/cleanup the new subdev notifiers.
> >    Reported by Rui Silva.
> > ---
> >   drivers/media/platform/video-mux.c         |  8 +++++++-
> >   drivers/media/v4l2-core/v4l2-fwnode.c      | 11 +----------
> >   drivers/staging/media/imx/imx6-mipi-csi2.c |  7 ++++++-
> >   drivers/staging/media/imx/imx7-media-csi.c |  7 ++++++-
> >   drivers/staging/media/imx/imx7-mipi-csis.c |  9 ++++++++-
> >   include/media/v4l2-fwnode.h                | 12 ++++++++----
> >   6 files changed, 36 insertions(+), 18 deletions(-)