Re: [RFC PATCH 2/8] media: i2c: ov6650: Drop implementation of .set_mbus_config()

From: Janusz Krzysztofik <jmkrzyszt@gmail.com>
To: Sakari Ailus <sakari.ailus@iki.fi>
Cc: "Laurent Pinchart" <laurent.pinchart@ideasonboard.com>,
	"Linux Media Mailing List" <linux-media@vger.kernel.org>,
	linux-renesas-soc@vger.kernel.org,
	"Hans Verkuil" <hverkuil-cisco@xs4all.nl>,
	"Kieran Bingham" <kieran.bingham@ideasonboard.com>,
	"Jacopo Mondi" <jacopo@jmondi.org>,
	"Niklas Söderlund" <niklas.soderlund@ragnatech.se>,
	"Tomi Valkeinen" <tomi.valkeinen@ideasonboard.com>
Subject: Re: [RFC PATCH 2/8] media: i2c: ov6650: Drop implementation of .set_mbus_config()
Date: Mon, 10 Jan 2022 19:11:45 +0100	[thread overview]
Message-ID: <1808044.CQOukoFCf9@dell> (raw)
In-Reply-To: <YdhDH/HmJ44B3Rxa@valkosipuli.retiisi.eu>

Hi Sakari,

On Friday, 7 January 2022 14:41:51 CET Sakari Ailus wrote:
> Hi Janusz,
> 
> On Wed, Jan 05, 2022 at 10:31:41PM +0100, Janusz Krzysztofik wrote:
> > Hi Laurent,
> > 
> > On Wednesday, 5 January 2022 21:19:49 CET Laurent Pinchart wrote:
> > > Hi Sakari,
> > >
> > > On Wed, Jan 05, 2022 at 08:04:24PM +0200, Sakari Ailus wrote:
> > > > On Mon, Jan 03, 2022 at 06:24:08PM +0200, Laurent Pinchart wrote:
> > > > > The subdev .set_mbus_config() operation is deprecated. No code in the
> > > > > kernel calls it, so drop its implementation from the ov6650 driver.
> > > > >
> > > > > Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> > > > > ---
> > > > >  drivers/media/i2c/ov6650.c | 37 -------------------------------------
> > > > >  1 file changed, 37 deletions(-)
> > > > >
> > > > > diff --git a/drivers/media/i2c/ov6650.c b/drivers/media/i2c/ov6650.c
> > > > > index f67412150b16..455a627e35a0 100644
> > > > > --- a/drivers/media/i2c/ov6650.c
> > > > > +++ b/drivers/media/i2c/ov6650.c
> > > > > @@ -944,42 +944,6 @@ static int ov6650_get_mbus_config(struct v4l2_subdev *sd,
> > > > >   return 0;
> > > > >  }
> > > > >
> > > > > -/* Alter bus settings on camera side */
> > > > > -static int ov6650_set_mbus_config(struct v4l2_subdev *sd,
> > > > > -                           unsigned int pad,
> > > > > -                           struct v4l2_mbus_config *cfg)
> > > > > -{
> > > > > - struct i2c_client *client = v4l2_get_subdevdata(sd);
> > > > > - int ret = 0;
> > > > > -
> > > > > - if (cfg->flags & V4L2_MBUS_PCLK_SAMPLE_RISING)
> > > > > -         ret = ov6650_reg_rmw(client, REG_COMJ, COMJ_PCLK_RISING, 0);
> > > > > - else if (cfg->flags & V4L2_MBUS_PCLK_SAMPLE_FALLING)
> > > > > -         ret = ov6650_reg_rmw(client, REG_COMJ, 0, COMJ_PCLK_RISING);
> > > >
> > > > I think this configuration should come from the endpoint which the driver
> > > > currently does not parse. In fact, there are no even DT bindings for the
> > > > device.
> > >
> > > There's also no OF match table. While this isn't strictly required, it
> > > may indicate that the sensor hasn't been tested much on DT-based
> > > systems.
> > >
> > > I agree that the configuration should come from the device tree, but I
> > > can't test that, so I'm tempted to let someone else implement it if the
> > > driver is actually still in use (I can also write a patch if someone can
> > > test it).
> > 
> > This driver was used with omap1_camera, removed from the tree a few years
> > ago by Hans, despite my attempts to refresh it.  I tried to keep ov6650
> > updated but I gave up due to lack of response to my submissions.  That also
> > blocked my attempts to rework and reintroduce omap1_camera.
> 
> My apologies for this --- I indeed to see a set of unreviewed ov6650 patches
> from you. Please do ping me if you expect an answer but do not get one.

OK, thanks.

> > I think I'm still able to update my local (v4l2, non-mc) version of
> > omap1_camera to the extent required to test any changes to ov6650.
> > However, the OMAP1 platform does not support DT, and will probably never
> > do.  Then,  I think that it makes sense to spend my time on that only if
> > you (media maintainers) are not going to depreciate non-DT support any
> > soon.  Are you?
> 
> Commenting just this and not the discussion later in this thread --- it is
> possible to support such sensor drivers without DT or ACPI nowadays,
> through software nodes. See e.g. drivers/media/pci/intel/ipu3/cio2-bridge.c

Thanks for bringing this possibility to my awareness, I didn't know it 
existed.  AFAICS, I2C sensor drivers like ov6650 can now be provided by 
board files with device properties via i2c_board_info.swnode.

If I find a solution to implement a non-v4l2-clk clock device in 
omap1_camera driver, I'll try to get back to updating ov6650 as time 
permits.

Thanks,
Janusz