linux-kernel - Re: [PATCH v2] media: qcom: camss: Add support for regulator init_load

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Message-ID: <d32cbtfzhwpzsvxpb7esvndpqxooergkzhlx2jp4ikuc3bsaop@gyxnlusuptg3>
Date: Mon, 11 Aug 2025 13:39:02 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Wenmeng Liu <quic_wenmliu@...cinc.com>
Cc: Robert Foss <rfoss@...nel.org>, Todor Tomov <todor.too@...il.com>,
        Bryan O'Donoghue <bryan.odonoghue@...aro.org>,
        Vladimir Zapolskiy <vladimir.zapolskiy@...aro.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] media: qcom: camss: Add support for regulator
 init_load_uA in CSIPHY

On Tue, Jul 29, 2025 at 03:24:55PM +0800, Wenmeng Liu wrote:
> Some Qualcomm regulators are configured with initial mode as
> HPM (High Power Mode), which may lead to higher power consumption.
> To reduce power usage, it's preferable to set the initial mode
> to LPM (Low Power Mode).
> 
> To ensure the regulator can switch from LPM to HPM when needed,
> this patch adds current load configuration for CAMSS CSIPHY.
> This allows the regulator framework to scale the mode dynamically
> based on the load requirement.
> 
> The current default value for current is uninitialized or random.
> To address this, initial current values are added for the
> following platforms:
> SDM670, SM8250, SC7280, SM8550, and X1E80100.
> 
> For SDM670, the value is set to -1, indicating that no default
> current value is configured, the other values are derived
> from the power grid.
> 
> ---
> Changes in v2:
> - Change the source of the current value from DTS to CAMSS resource
> - Link to v1: https://lore.kernel.org/all/20250620040736.3032667-1-quic_wenmliu@quicinc.com/
> ---
> 
> Signed-off-by: Wenmeng Liu <quic_wenmliu@...cinc.com>
> ---
>  drivers/media/platform/qcom/camss/camss-csiphy.c |  4 +++-
>  drivers/media/platform/qcom/camss/camss.c        | 26 ++++++++++++++++++++++++
>  drivers/media/platform/qcom/camss/camss.h        |  1 +
>  3 files changed, 30 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/platform/qcom/camss/camss-csiphy.c b/drivers/media/platform/qcom/camss/camss-csiphy.c
> index 2de97f58f9ae4f91e8bba39dcadf92bea8cf6f73..7a2d80a03dbd0884b614451b55cd27dce94af637 100644
> --- a/drivers/media/platform/qcom/camss/camss-csiphy.c
> +++ b/drivers/media/platform/qcom/camss/camss-csiphy.c
> @@ -707,8 +707,10 @@ int msm_csiphy_subdev_init(struct camss *camss,
>  			return -ENOMEM;
>  	}
>  
> -	for (i = 0; i < csiphy->num_supplies; i++)
> +	for (i = 0; i < csiphy->num_supplies; i++) {
>  		csiphy->supplies[i].supply = res->regulators[i];
> +		csiphy->supplies[i].init_load_uA = res->regulators_current[i];

Could you possibly refactor to use devm_regulator_bulk_get_const()? It
would save you from this data moving.

> +	}
>  
>  	ret = devm_regulator_bulk_get(camss->dev, csiphy->num_supplies,
>  				      csiphy->supplies);
> diff --git a/drivers/media/platform/qcom/camss/camss.c b/drivers/media/platform/qcom/camss/camss.c
> index e08e70b93824baa5714b3a736bc1d05405253aaa..daf21c944c2b4818b1656efc255e817551788658 100644
> --- a/drivers/media/platform/qcom/camss/camss.c
> +++ b/drivers/media/platform/qcom/camss/camss.c
> @@ -750,6 +750,7 @@ static const struct camss_subdev_resources csiphy_res_670[] = {
>  	/* CSIPHY0 */
>  	{
>  		.regulators = { "vdda-phy", "vdda-pll" },
> +		.regulators_current = { -1, -1 },

If it's unset, it should be 0, not -1.

>  		.clock = { "soc_ahb", "cpas_ahb",
>  			   "csiphy0", "csiphy0_timer" },
>  		.clock_rate = { { 0 },

-- 
With best wishes
Dmitry