linux-kernel - Re: [PATCH 1/2] media: i2c: max96714: add HAS

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Message-ID: <20240912121816.GC25276@pendragon.ideasonboard.com>
Date: Thu, 12 Sep 2024 15:18:16 +0300
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc: Tommaso Merciai <tomm.merciai@...il.com>, linuxfancy@...glegroups.com,
	julien.massot@...labora.com,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] media: i2c: max96714: add HAS_EVENTS subdev flag

On Thu, Sep 12, 2024 at 12:14:52PM +0000, Sakari Ailus wrote:
> On Thu, Sep 12, 2024 at 03:05:10PM +0300, Laurent Pinchart wrote:
> > On Thu, Sep 12, 2024 at 01:11:13PM +0200, Tommaso Merciai wrote:
> > > On Thu, Sep 12, 2024 at 01:44:09PM +0300, Laurent Pinchart wrote:
> > > > On Tue, Sep 10, 2024 at 03:44:27PM +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 flag.
> > > > 
> > > > How is this supposed to work, given that the driver doesn't implement
> > > > .subscribe_event() ?
> > > 
> > > You are completely right, sorry.
> > > I think in both cases I'm missing:
> > > 
> > > diff --git a/drivers/media/i2c/max96714.c b/drivers/media/i2c/max96714.c
> > > index 94b1bc000e48..2257b6b807ea 100644
> > > --- a/drivers/media/i2c/max96714.c
> > > +++ b/drivers/media/i2c/max96714.c
> > > @@ -17,6 +17,7 @@
> > > 
> > >  #include <media/v4l2-cci.h>
> > >  #include <media/v4l2-ctrls.h>
> > > +#include <media/v4l2-event.h>
> > >  #include <media/v4l2-fwnode.h>
> > >  #include <media/v4l2-subdev.h>
> > > 
> > > @@ -488,6 +489,8 @@ static int max96714_log_status(struct v4l2_subdev *sd)
> > > 
> > >  static const struct v4l2_subdev_core_ops max96714_subdev_core_ops = {
> > >         .log_status = max96714_log_status,
> > > +       .subscribe_event = v4l2_ctrl_subdev_subscribe_event,
> > > +       .unsubscribe_event = v4l2_event_subdev_unsubscribe,
> > >  };
> > > 
> > >  static const struct v4l2_subdev_video_ops max96714_video_ops = {
> > > 
> > > Like you suggest. Or I'm wrong?
> > 
> > That looks better :-)
> > 
> > Out of curiosity, what's your use case for control events ?
> 
> I'm not sure if there's a use case, however control event should be
> supported when a driver supports controls.

Not disputing that. That's why I asked "out of curiosity".

-- 
Regards,

Laurent Pinchart