linux-kernel - Re: [PATCH] regulator: qcom_smd: Keep one rpm handle for all vregs

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Date: Wed, 27 Dec 2023 13:48:05 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Konrad Dybcio <konrad.dybcio@...aro.org>,
 Bjorn Andersson <andersson@...nel.org>, Liam Girdwood <lgirdwood@...il.com>,
 Mark Brown <broonie@...nel.org>
Cc: Marijn Suijten <marijn.suijten@...ainline.org>,
 linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] regulator: qcom_smd: Keep one rpm handle for all vregs

On 27/12/2023 03:29, Konrad Dybcio wrote:
> For no apparent reason (as there's just one RPM per SoC), all vregs
> currently store a copy of a pointer to smd_rpm. Introduce a single,
> global one to save up on space in each definition.
> 
> bloat-o-meter reports:
> 
> Total: Before=43944, After=43924, chg -0.05%
> 
> plus sizeof(ptr) on every dynamically allocated regulator :)
> 
> Signed-off-by: Konrad Dybcio <konrad.dybcio@...aro.org>
> ---
>   drivers/regulator/qcom_smd-regulator.c | 18 +++++++-----------
>   1 file changed, 7 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/regulator/qcom_smd-regulator.c b/drivers/regulator/qcom_smd-regulator.c
> index d1be9568025e..905c15df8c85 100644
> --- a/drivers/regulator/qcom_smd-regulator.c
> +++ b/drivers/regulator/qcom_smd-regulator.c
> @@ -11,11 +11,10 @@
>   #include <linux/regulator/of_regulator.h>
>   #include <linux/soc/qcom/smd-rpm.h>
>   
> +struct qcom_smd_rpm *smd_vreg_rpm;
> +
>   struct qcom_rpm_reg {
>   	struct device *dev;
> -
> -	struct qcom_smd_rpm *rpm;
> -
>   	u32 type;
>   	u32 id;
>   
> @@ -70,7 +69,7 @@ static int rpm_reg_write_active(struct qcom_rpm_reg *vreg)
>   	if (!reqlen)
>   		return 0;
>   
> -	ret = qcom_rpm_smd_write(vreg->rpm, QCOM_SMD_RPM_ACTIVE_STATE,
> +	ret = qcom_rpm_smd_write(smd_vreg_rpm, QCOM_SMD_RPM_ACTIVE_STATE,
>   				 vreg->type, vreg->id,
>   				 req, sizeof(req[0]) * reqlen);
>   	if (!ret) {
> @@ -1391,7 +1390,7 @@ MODULE_DEVICE_TABLE(of, rpm_of_match);
>    * Return: 0 on success, errno on failure
>    */
>   static int rpm_regulator_init_vreg(struct qcom_rpm_reg *vreg, struct device *dev,
> -				   struct device_node *node, struct qcom_smd_rpm *rpm,
> +				   struct device_node *node,
>   				   const struct rpm_regulator_data *pmic_rpm_data)
>   {
>   	struct regulator_config config = {};
> @@ -1409,7 +1408,6 @@ static int rpm_regulator_init_vreg(struct qcom_rpm_reg *vreg, struct device *dev
>   	}
>   
>   	vreg->dev	= dev;
> -	vreg->rpm	= rpm;
>   	vreg->type	= rpm_data->type;
>   	vreg->id	= rpm_data->id;
>   
> @@ -1440,11 +1438,10 @@ static int rpm_reg_probe(struct platform_device *pdev)
>   	const struct rpm_regulator_data *vreg_data;
>   	struct device_node *node;
>   	struct qcom_rpm_reg *vreg;
> -	struct qcom_smd_rpm *rpm;
>   	int ret;
>   
> -	rpm = dev_get_drvdata(pdev->dev.parent);
> -	if (!rpm) {
> +	smd_vreg_rpm = dev_get_drvdata(pdev->dev.parent);
> +	if (!smd_vreg_rpm) {

I thought about having a mutex around (I don't remember if secondary 
PMICs and/or chargers can be routed through RPM or not).

Then I went on checking other RPM and SMD-RPM drivers.

clk-rpm: global variable, field
clk-smd-rpm: struct field
regulator_qcom-smd-rpm: struct field

Probably it's worth using the same approach in all four drivers?

>   		dev_err(&pdev->dev, "Unable to retrieve handle to rpm\n");
>   		return -ENODEV;
>   	}
> @@ -1460,8 +1457,7 @@ static int rpm_reg_probe(struct platform_device *pdev)
>   			return -ENOMEM;
>   		}
>   
> -		ret = rpm_regulator_init_vreg(vreg, dev, node, rpm, vreg_data);
> -
> +		ret = rpm_regulator_init_vreg(vreg, dev, node, vreg_data);
>   		if (ret < 0) {
>   			of_node_put(node);
>   			return ret;
> 
> ---
> base-commit: 39676dfe52331dba909c617f213fdb21015c8d10
> change-id: 20231227-topic-rpm_vreg_cleanup-fa095cd528ec
> 
> Best regards,

-- 
With best wishes
Dmitry