linux-kernel - Re: [PATCH v1 41/55] media: i2c: ov8865: Use the v4l2 helper for obtaining the clock

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Message-ID: <aFZmPOqYz0Rgv5H0@valkosipuli.retiisi.eu>
Date: Sat, 21 Jun 2025 07:58:52 +0000
From: Sakari Ailus <sakari.ailus@....fi>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc: Mehdi Djait <mehdi.djait@...ux.intel.com>, sakari.ailus@...ux.intel.com,
	akinobu.mita@...il.com, stanislaw.gruszka@...ux.intel.com,
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Subject: Re: [PATCH v1 41/55] media: i2c: ov8865: Use the v4l2 helper for
 obtaining the clock

Hi Laurent,

On Fri, Jun 20, 2025 at 12:59:51AM +0300, Laurent Pinchart wrote:
> On Fri, Jun 20, 2025 at 12:57:46AM +0300, Laurent Pinchart wrote:
> > Hi Mehdi,
> > 
> > Thank you for the patch.
> > 
> > On Thu, Jun 19, 2025 at 07:59:34PM +0200, Mehdi Djait wrote:
> > > devm_clk_get() fails on ACPI-based platforms, where firmware does not
> > > provide a direct reference to the clock producer.
> > > 
> > > Replace devm_clk_get() with the new v4l2 helper
> > > devm_v4l2_sensor_clk_get() that works on both DT- and ACPI-based
> > > platforms to retrieve a reference to the clock producer from firmware.
> > > 
> > > Signed-off-by: Mehdi Djait <mehdi.djait@...ux.intel.com>
> > 
> > Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
> > 
> > > 
> > > diff --git a/drivers/media/i2c/ov8865.c b/drivers/media/i2c/ov8865.c
> > > index 95ffe7536aa6..5cc278c3e169 100644
> > > --- a/drivers/media/i2c/ov8865.c
> > > +++ b/drivers/media/i2c/ov8865.c
> > > @@ -2956,7 +2956,6 @@ static int ov8865_probe(struct i2c_client *client)
> > >  	struct ov8865_sensor *sensor;
> > >  	struct v4l2_subdev *subdev;
> > >  	struct media_pad *pad;
> > > -	unsigned int rate = 0;
> > >  	unsigned int i;
> > >  	int ret;
> > >  
> > > @@ -3019,39 +3018,14 @@ static int ov8865_probe(struct i2c_client *client)
> > >  
> > >  	/* External Clock */
> > >  
> > > -	sensor->extclk = devm_clk_get(dev, NULL);
> > > -	if (PTR_ERR(sensor->extclk) == -ENOENT) {
> > > -		dev_info(dev, "no external clock found, continuing...\n");
> > > -		sensor->extclk = NULL;
> > > -	} else if (IS_ERR(sensor->extclk)) {
> > > +	sensor->extclk = devm_v4l2_sensor_clk_get(dev, NULL);
> > > +	if (IS_ERR(sensor->extclk)) {
> > >  		dev_err(dev, "failed to get external clock\n");
> > >  		ret = PTR_ERR(sensor->extclk);
> 
> Actually, I'd take this as an opportunity to write
> 
>  		ret = dev_err_probe(dev, PTR_ERR(sensor->extclk),
> 				    "failed to get external clock\n");

Wouldn't printing this kind of a message fit for devm_v4l2_sensor_clk_get()
and consequently be removed from drivers?

-- 
Kind regards,

Sakari Ailus