linux-kernel - Re: [PATCH] media: i2c: rdacm2x: properly set subdev entity function

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Date:   Wed, 9 Mar 2022 11:29:44 +0200
From:   Laurentiu Palcu <laurentiu.palcu@....nxp.com>
To:     Jacopo Mondi <jacopo@...ndi.org>
Cc:     Jacopo Mondi <jacopo+renesas@...ndi.org>,
        Kieran Bingham <kieran.bingham+renesas@...asonboard.com>,
        Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>,
        Niklas Söderlund 
        <niklas.soderlund+renesas@...natech.se>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] media: i2c: rdacm2x: properly set subdev entity function

Hi Jacopo,

On Wed, Mar 09, 2022 at 09:43:11AM +0100, Jacopo Mondi wrote:
> Hi Laurentiu,
> 
> On Tue, Mar 08, 2022 at 02:55:49PM +0200, Laurentiu Palcu wrote:
> > The subdevice entity function was left unset, which produces a warning
> > when probing the device:
> >
> > mxc-md bus@...00000:camera: Entity type for entity rdacm20 19-0051 was
> > not initialized!
> >
> > Also, set the entity flags to MEDIA_ENT_FL_DEFAULT instead of
> > MEDIA_ENT_F_CAM_SENSOR which will be used for entity's function instead.
> >
> > Signed-off-by: Laurentiu Palcu <laurentiu.palcu@....nxp.com>
> > ---
> > Hi,
> >
> > Only tested the rdacm20 part but I believe rdacm21 should work as well.
> >
> > Cheers,
> > laurentiu
> >
> >  drivers/media/i2c/rdacm20.c | 3 ++-
> >  drivers/media/i2c/rdacm21.c | 3 ++-
> >  2 files changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/media/i2c/rdacm20.c b/drivers/media/i2c/rdacm20.c
> > index 025a610de893..ea5b7d5151ee 100644
> > --- a/drivers/media/i2c/rdacm20.c
> > +++ b/drivers/media/i2c/rdacm20.c
> > @@ -611,7 +611,8 @@ static int rdacm20_probe(struct i2c_client *client)
> >  		goto error_free_ctrls;
> >
> >  	dev->pad.flags = MEDIA_PAD_FL_SOURCE;
> > -	dev->sd.entity.flags |= MEDIA_ENT_F_CAM_SENSOR;
> > +	dev->sd.entity.flags |= MEDIA_ENT_FL_DEFAULT;
> 
> I'm not sure if setting the DEFAULT flag is right:
> 
>  * %MEDIA_ENT_FL_DEFAULT
>  *    indicates the default entity for a given type.
>  *    This can be used to report the default audio and video devices or the
>  *    default camera sensor.
> 
> In a typical setup there will be several RDACM2x in use, marking all
> of them as "default" seems not right (if I understood the flag
> description right).

My initial thought was to not set the entity flags at all. However,
since the old code had the flags set to MEDIA_ENT_F_CAM_SENSOR which is,
essentially, 0x20001, setting it to MEDIA_ENT_FL_DEFAULT (1 << 0) would
mean, basically, the same thing and would not affect existing user apps
that might already probe that flag... Removing the flag now might
potentially break existing apps. :/

Are there any other opinions on this one?

> 
> 
> > +	dev->sd.entity.function = MEDIA_ENT_F_CAM_SENSOR;
> 
> This seems right, and it's probably worth a Fixes tag?

I'll send a v2 with the Fixes tag which I meant to add but totally
forgot...

Cheers,
Laurentiu

> 
> Thanks
>    j
> 
> >  	ret = media_entity_pads_init(&dev->sd.entity, 1, &dev->pad);
> >  	if (ret < 0)
> >  		goto error_free_ctrls;
> > diff --git a/drivers/media/i2c/rdacm21.c b/drivers/media/i2c/rdacm21.c
> > index 12ec5467ed1e..be89bd43e88b 100644
> > --- a/drivers/media/i2c/rdacm21.c
> > +++ b/drivers/media/i2c/rdacm21.c
> > @@ -583,7 +583,8 @@ static int rdacm21_probe(struct i2c_client *client)
> >  		goto error_free_ctrls;
> >
> >  	dev->pad.flags = MEDIA_PAD_FL_SOURCE;
> > -	dev->sd.entity.flags |= MEDIA_ENT_F_CAM_SENSOR;
> > +	dev->sd.entity.flags |= MEDIA_ENT_FL_DEFAULT;
> > +	dev->sd.entity.function = MEDIA_ENT_F_CAM_SENSOR;
> >  	ret = media_entity_pads_init(&dev->sd.entity, 1, &dev->pad);
> >  	if (ret < 0)
> >  		goto error_free_ctrls;
> > --
> > 2.33.0
> >