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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250619215951.GA32257@pendragon.ideasonboard.com>
Date: Fri, 20 Jun 2025 00:59:51 +0300
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Mehdi Djait <mehdi.djait@...ux.intel.com>
Cc: sakari.ailus@...ux.intel.com, akinobu.mita@...il.com,
	stanislaw.gruszka@...ux.intel.com, hdegoede@...hat.com,
	arnd@...db.de, alain.volmat@...s.st.com, andrzej.hajda@...el.com,
	benjamin.mugnier@...s.st.com, dave.stevenson@...pberrypi.com,
	hansg@...nel.org, hverkuil@...all.nl, jacopo.mondi@...asonboard.com,
	jonas@...boo.se, kieran.bingham@...asonboard.com, khalasa@...p.pl,
	prabhakar.csengg@...il.com, mani@...nel.org,
	m.felsch@...gutronix.de, martink@...teo.de, mattwmajewski@...il.com,
	matthias.fend@...end.at, mchehab@...nel.org,
	michael.riesch@...labora.com, naush@...pberrypi.com,
	nicholas@...hemail.net, nicolas.dufresne@...labora.com,
	paul.elder@...asonboard.com, dan.scally@...asonboard.com,
	pavel@...nel.org, petrcvekcz@...il.com, rashanmu@...il.com,
	ribalda@...omium.org, rmfrfs@...il.com, zhengsq@...k-chips.com,
	slongerbeam@...il.com, sylvain.petinot@...s.st.com,
	s.nawrocki@...sung.com, tomi.valkeinen@...asonboard.com,
	umang.jain@...asonboard.com, zhi.mao@...iatek.com,
	linux-kernel@...r.kernel.org, linux-media@...r.kernel.org
Subject: Re: [PATCH v1 41/55] media: i2c: ov8865: Use the v4l2 helper for
 obtaining the clock

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");

> >  		goto error_endpoint;
> >  	}
> >  
> > -	/*
> > -	 * We could have either a 24MHz or 19.2MHz clock rate from either dt or
> > -	 * ACPI...but we also need to support the weird IPU3 case which will
> > -	 * have an external clock AND a clock-frequency property. Check for the
> > -	 * clock-frequency property and if found, set that rate if we managed
> > -	 * to acquire a clock. This should cover the ACPI case. If the system
> > -	 * uses devicetree then the configured rate should already be set, so
> > -	 * we can just read it.
> > -	 */
> > -	ret = fwnode_property_read_u32(dev_fwnode(dev), "clock-frequency",
> > -				       &rate);
> > -	if (!ret && sensor->extclk) {
> > -		ret = clk_set_rate(sensor->extclk, rate);
> > -		if (ret) {
> > -			dev_err_probe(dev, ret, "failed to set clock rate\n");
> > -			goto error_endpoint;
> > -		}
> > -	} else if (ret && !sensor->extclk) {
> > -		dev_err_probe(dev, ret, "invalid clock config\n");
> > -		goto error_endpoint;
> > -	}
> > -
> > -	sensor->extclk_rate = rate ? rate : clk_get_rate(sensor->extclk);
> > +	sensor->extclk_rate = clk_get_rate(sensor->extclk);
> >  
> >  	for (i = 0; i < ARRAY_SIZE(supported_extclk_rates); i++) {
> >  		if (sensor->extclk_rate == supported_extclk_rates[i])

-- 
Regards,

Laurent Pinchart