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

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Message-ID: <20250619215744.GS22102@pendragon.ideasonboard.com>
Date: Fri, 20 Jun 2025 00:57:44 +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,
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	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

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);
>  		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