linux-kernel - Re: [PATCH v5 2/5] media: i2c: ov5645: Drop reading clock-frequency dt-property

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Date:   Mon, 6 Apr 2020 20:34:25 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Cc:     Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Kieran Bingham <kieran.bingham+renesas@...asonboard.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        linux-media@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Lad Prabhakar <prabhakar.csengg@...il.com>
Subject: Re: [PATCH v5 2/5] media: i2c: ov5645: Drop reading clock-frequency
 dt-property

Hi Prabhakar,

Thank you for the patch.

On Mon, Apr 06, 2020 at 05:42:38PM +0100, Lad Prabhakar wrote:
> Modes in the driver are based on xvclk frequency fixed to 24MHz, but where
> as the OV5645 sensor can support the xvclk frequency ranging from 6MHz to
> 24MHz. So instead making clock-frequency as dt-property just let the
> driver enforce the required clock frequency.
> 
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> ---
>  drivers/media/i2c/ov5645.c | 14 +++++---------
>  1 file changed, 5 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/media/i2c/ov5645.c b/drivers/media/i2c/ov5645.c
> index a6c17d15d754..52848fff8a08 100644
> --- a/drivers/media/i2c/ov5645.c
> +++ b/drivers/media/i2c/ov5645.c
> @@ -61,6 +61,8 @@
>  #define OV5645_SDE_SAT_U		0x5583
>  #define OV5645_SDE_SAT_V		0x5584
>  
> +#define OV5645_XVCLK_FREQ		24000000
> +
>  /* regulator supplies */
>  static const char * const ov5645_supply_name[] = {
>  	"vdddo", /* Digital I/O (1.8V) supply */
> @@ -1094,25 +1096,19 @@ static int ov5645_probe(struct i2c_client *client)
>  		return PTR_ERR(ov5645->xclk);
>  	}
>  
> -	ret = of_property_read_u32(dev->of_node, "clock-frequency", &xclk_freq);
> +	ret = clk_set_rate(ov5645->xclk, OV5645_XVCLK_FREQ);
>  	if (ret) {
> -		dev_err(dev, "could not get xclk frequency\n");
> +		dev_err(dev, "could not set xclk frequency\n");
>  		return ret;
>  	}
> -

I think you can keep the blank line here.

Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

>  	/* external clock must be 24MHz, allow 1% tolerance */
> +	xclk_freq = clk_get_rate(ov5645->xclk);
>  	if (xclk_freq < 23760000 || xclk_freq > 24240000) {
>  		dev_err(dev, "external clock frequency %u is not supported\n",
>  			xclk_freq);
>  		return -EINVAL;
>  	}
>  
> -	ret = clk_set_rate(ov5645->xclk, xclk_freq);
> -	if (ret) {
> -		dev_err(dev, "could not set xclk frequency\n");
> -		return ret;
> -	}
> -
>  	for (i = 0; i < OV5645_NUM_SUPPLIES; i++)
>  		ov5645->supplies[i].supply = ov5645_supply_name[i];
>  

-- 
Regards,

Laurent Pinchart