linux-kernel - Re: [PATCH] media: i2c: ov5645: add HAS

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Message-ID: <Zw4IrU8bOOtq26Gx@tom-HP-ZBook-Fury-15-G7-Mobile-Workstation>
Date: Tue, 15 Oct 2024 08:16:13 +0200
From: Tommaso Merciai <tomm.merciai@...il.com>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc: sakari.ailus@...ux.intel.com,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] media: i2c: ov5645: add HAS_EVENTS support

Hi Laurent,
Thanks for your review.

On Mon, Oct 14, 2024 at 08:54:52PM +0300, Laurent Pinchart wrote:
> Hi Tommaso,
> 
> Thank you for the patch.
> 
> On Mon, Oct 14, 2024 at 07:38:40PM +0200, Tommaso Merciai wrote:
> > Controls can be exposed to userspace via a v4l-subdevX device, and
> > userspace has to be able to subscribe to control events so that it is
> > notified when the control changes value.
> > Add missing HAS_EVENTS support: flag and .(un)subscribe_event().
> > 
> > Signed-off-by: Tommaso Merciai <tomm.merciai@...il.com>
> > ---
> >  drivers/media/i2c/ov5645.c | 10 +++++++++-
> >  1 file changed, 9 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/media/i2c/ov5645.c b/drivers/media/i2c/ov5645.c
> > index 0c32bd2940ec..2c5145d5c616 100644
> > --- a/drivers/media/i2c/ov5645.c
> > +++ b/drivers/media/i2c/ov5645.c
> > @@ -29,6 +29,7 @@
> >  #include <linux/slab.h>
> >  #include <linux/types.h>
> >  #include <media/v4l2-ctrls.h>
> > +#include <media/v4l2-event.h>
> >  #include <media/v4l2-fwnode.h>
> >  #include <media/v4l2-subdev.h>
> >  
> > @@ -1034,6 +1035,11 @@ static const struct v4l2_subdev_video_ops ov5645_video_ops = {
> >  	.s_stream = ov5645_s_stream,
> >  };
> >  
> > +static const struct v4l2_subdev_core_ops ov5645_subdev_core_ops = {
> > +	.subscribe_event = v4l2_ctrl_subdev_subscribe_event,
> > +	.unsubscribe_event = v4l2_event_subdev_unsubscribe,
> > +};
> > +
> >  static const struct v4l2_subdev_pad_ops ov5645_subdev_pad_ops = {
> >  	.enum_mbus_code = ov5645_enum_mbus_code,
> >  	.enum_frame_size = ov5645_enum_frame_size,
> > @@ -1043,6 +1049,7 @@ static const struct v4l2_subdev_pad_ops ov5645_subdev_pad_ops = {
> >  };
> >  
> >  static const struct v4l2_subdev_ops ov5645_subdev_ops = {
> > +	.core = &ov5645_subdev_core_ops,
> >  	.video = &ov5645_video_ops,
> >  	.pad = &ov5645_subdev_pad_ops,
> >  };
> > @@ -1178,7 +1185,8 @@ static int ov5645_probe(struct i2c_client *client)
> >  
> >  	v4l2_i2c_subdev_init(&ov5645->sd, client, &ov5645_subdev_ops);
> >  	ov5645->sd.internal_ops = &ov5645_internal_ops;
> > -	ov5645->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
> > +	ov5645->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE |
> > +			    V4L2_SUBDEV_FL_HAS_EVENTS;
> 
> Instead of patching every subdev driver, should we handle all of this in
> the subdev core ? If a control handler is set for the subdev, we could
> set the HAS_EVENTS flag automatically, and default to
> v4l2_ctrl_subdev_subscribe_event() and v4l2_event_subdev_unsubscribe()
> if there are no control operations.

Well :)
Not every subdev drivers, but only the ones I'm testing.

Yesterday I was playing with ov5645 :) And I got:

v4l2-compliance -d /dev/v4l-subdev1

test VIDIOC_G/S/TRY_EXT_CTRLS: OK
fail: v4l2-test-controls.cpp(1108): subscribe event for control 'User Controls' failed

Joke apart fully agree and thanks for your hint!
I will take  a look :)

> 
> >  	ov5645->pad.flags = MEDIA_PAD_FL_SOURCE;
> >  	ov5645->sd.dev = &client->dev;
> >  	ov5645->sd.entity.function = MEDIA_ENT_F_CAM_SENSOR;
> 
> -- 
> Regards,
> 
> Laurent Pinchart

Thanks & Regards,
Tommaso