linux-kernel - Re: [PATCH v7 2/5] media: imx8mq-mipi-csi2: Use devm_clk_bulk_get

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Message-ID: <20251027001151.GN13023@pendragon.ideasonboard.com>
Date: Mon, 27 Oct 2025 02:11:51 +0200
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Guoniu Zhou <guoniu.zhou@....nxp.com>
Cc: Rui Miguel Silva <rmfrfs@...il.com>,
	Martin Kepplinger <martink@...teo.de>,
	Purism Kernel Team <kernel@...i.sm>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>,
	Philipp Zabel <p.zabel@...gutronix.de>, Frank Li <Frank.Li@....com>,
	linux-media@...r.kernel.org, devicetree@...r.kernel.org,
	imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, Guoniu Zhou <guoniu.zhou@....com>
Subject: Re: [PATCH v7 2/5] media: imx8mq-mipi-csi2: Use
 devm_clk_bulk_get_all() to fetch clocks

On Thu, Oct 23, 2025 at 05:19:43PM +0800, Guoniu Zhou wrote:
> From: Guoniu Zhou <guoniu.zhou@....com>
> 
> Use devm_clk_bulk_get_all() helper to simplify clock handle code.
> 
> No functional changes intended.
> 
> Reviewed-by: Frank Li <Frank.Li@....com>
> Signed-off-by: Guoniu Zhou <guoniu.zhou@....com>
> ---
>  drivers/media/platform/nxp/imx8mq-mipi-csi2.c | 52 ++++++++-------------------
>  1 file changed, 15 insertions(+), 37 deletions(-)
> 
> diff --git a/drivers/media/platform/nxp/imx8mq-mipi-csi2.c b/drivers/media/platform/nxp/imx8mq-mipi-csi2.c
> index d333ff43539f061b8b9cf88af2cda8c44b3ec2a9..fd202601d401145da8be23df4451f6af660642c5 100644
> --- a/drivers/media/platform/nxp/imx8mq-mipi-csi2.c
> +++ b/drivers/media/platform/nxp/imx8mq-mipi-csi2.c
> @@ -71,21 +71,6 @@ enum {
>  	ST_SUSPENDED	= 4,
>  };
>  
> -enum imx8mq_mipi_csi_clk {
> -	CSI2_CLK_CORE,
> -	CSI2_CLK_ESC,
> -	CSI2_CLK_UI,
> -	CSI2_NUM_CLKS,
> -};
> -
> -static const char * const imx8mq_mipi_csi_clk_id[CSI2_NUM_CLKS] = {
> -	[CSI2_CLK_CORE] = "core",
> -	[CSI2_CLK_ESC] = "esc",
> -	[CSI2_CLK_UI] = "ui",
> -};
> -
> -#define CSI2_NUM_CLKS	ARRAY_SIZE(imx8mq_mipi_csi_clk_id)
> -
>  struct imx8mq_plat_data {
>  	int (*enable)(struct csi_state *state, u32 hs_settle);
>  	void (*disable)(struct csi_state *state);
> @@ -111,7 +96,8 @@ struct csi_state {
>  	struct device *dev;
>  	const struct imx8mq_plat_data *pdata;
>  	void __iomem *regs;
> -	struct clk_bulk_data clks[CSI2_NUM_CLKS];
> +	struct clk_bulk_data *clks;
> +	int num_clks;
>  	struct reset_control *rst;
>  	struct regulator *mipi_phy_regulator;
>  
> @@ -384,24 +370,16 @@ static void imx8mq_mipi_csi_set_params(struct csi_state *state)
>  			      CSI2RX_SEND_LEVEL);
>  }
>  
> -static int imx8mq_mipi_csi_clk_enable(struct csi_state *state)
> -{
> -	return clk_bulk_prepare_enable(CSI2_NUM_CLKS, state->clks);
> -}
> -
> -static void imx8mq_mipi_csi_clk_disable(struct csi_state *state)
> +static struct clk *find_esc_clk(struct csi_state *state)

This is one of the reasons why I don't like devm_clk_bulk_get_all(). I
won't object to this patch, but I don't like it. At the very lest, you
should look up the clock at probe time and cache it in the
imx8mq_plat_data structure, to avoid looking it up multiple times at
runtime.

>  {
> -	clk_bulk_disable_unprepare(CSI2_NUM_CLKS, state->clks);
> -}
> -
> -static int imx8mq_mipi_csi_clk_get(struct csi_state *state)
> -{
> -	unsigned int i;
> +	int i;
>  
> -	for (i = 0; i < CSI2_NUM_CLKS; i++)
> -		state->clks[i].id = imx8mq_mipi_csi_clk_id[i];
> +	for (i = 0; i < state->num_clks; i++) {

Make state->num_clks unsigned instead of making i signed.

> +		if (!strcmp(state->clks[i].id, "esc"))
> +			return state->clks[i].clk;
> +	}
>  
> -	return devm_clk_bulk_get(state->dev, CSI2_NUM_CLKS, state->clks);
> +	return NULL;

This needs to become a probe error.

>  }
>  
>  static int imx8mq_mipi_csi_calc_hs_settle(struct csi_state *state,
> @@ -456,7 +434,7 @@ static int imx8mq_mipi_csi_calc_hs_settle(struct csi_state *state,
>  	 * documentation recommends picking a value away from the boundaries.
>  	 * Let's pick the average.
>  	 */
> -	esc_clk_rate = clk_get_rate(state->clks[CSI2_CLK_ESC].clk);
> +	esc_clk_rate = clk_get_rate(find_esc_clk(state));
>  	if (!esc_clk_rate) {
>  		dev_err(state->dev, "Could not get esc clock rate.\n");
>  		return -EINVAL;
> @@ -783,7 +761,7 @@ static void imx8mq_mipi_csi_pm_suspend(struct device *dev)
>  
>  	if (state->state & ST_POWERED) {
>  		imx8mq_mipi_csi_stop_stream(state);
> -		imx8mq_mipi_csi_clk_disable(state);
> +		clk_bulk_disable_unprepare(state->num_clks, state->clks);
>  		state->state &= ~ST_POWERED;
>  	}
>  
> @@ -801,7 +779,7 @@ static int imx8mq_mipi_csi_pm_resume(struct device *dev)
>  
>  	if (!(state->state & ST_POWERED)) {
>  		state->state |= ST_POWERED;
> -		ret = imx8mq_mipi_csi_clk_enable(state);
> +		ret = clk_bulk_prepare_enable(state->num_clks, state->clks);
>  	}
>  	if (state->state & ST_STREAMING) {
>  		sd_state = v4l2_subdev_lock_and_get_active_state(sd);
> @@ -1027,9 +1005,9 @@ static int imx8mq_mipi_csi_probe(struct platform_device *pdev)
>  	if (IS_ERR(state->regs))
>  		return PTR_ERR(state->regs);
>  
> -	ret = imx8mq_mipi_csi_clk_get(state);
> -	if (ret < 0)
> -		return ret;
> +	state->num_clks = devm_clk_bulk_get_all(dev, &state->clks);
> +	if (state->num_clks < 0)
> +		return dev_err_probe(dev, state->num_clks, "Failed to get clocks\n");
>  
>  	platform_set_drvdata(pdev, &state->sd);
>  

-- 
Regards,

Laurent Pinchart