linux-kernel - Re: [PATCH 1/2] clk: qcom: common: Add support for power-domain attachment

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Message-ID: <u6azgqlmncadcwiz42pk36q7rehwajnftvwfjh4aoawskdwkof@ao2imoy34k4y>
Date: Tue, 19 Nov 2024 09:41:19 -0600
From: Bjorn Andersson <andersson@...nel.org>
To: Bryan O'Donoghue <bryan.odonoghue@...aro.org>
Cc: Michael Turquette <mturquette@...libre.com>, 
	Stephen Boyd <sboyd@...nel.org>, linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] clk: qcom: common: Add support for power-domain
 attachment

On Mon, Nov 18, 2024 at 02:24:32AM +0000, Bryan O'Donoghue wrote:
> Right now we have a plethora of singleton power-domains which power clock
> controllers. These singletons are switched on by core logic when we probe
> the clocks.
> 
> However when multiple power-domains are attached to a clock controller that
> list of power-domains needs to be managed outside of core logic.
> 

I'd prefer if you rewrote this to make it clearer for the broader
audience what exactly you mean with "singleton" and "core logic".

> Use dev_pm_domain_attach_list() to automatically hook the list of given
> power-domains in the dtsi for the clock being registered in
> qcom_cc_really_probe().
> 

Do we need to power on/off all the associated power-domains every time
we access registers in the clock controller etc, or only in relation to
operating these GDSCs?

Regards,
Bjorn

> Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@...aro.org>
> ---
>  drivers/clk/qcom/common.c | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
> 
> diff --git a/drivers/clk/qcom/common.c b/drivers/clk/qcom/common.c
> index 33cc1f73c69d1f875a193aea0552902268dc8716..b4377fa09f7c0ec8d3c63dfc97d04fbb8cd6e10b 100644
> --- a/drivers/clk/qcom/common.c
> +++ b/drivers/clk/qcom/common.c
> @@ -22,6 +22,7 @@ struct qcom_cc {
>  	struct qcom_reset_controller reset;
>  	struct clk_regmap **rclks;
>  	size_t num_rclks;
> +	struct dev_pm_domain_list *pd_list;
>  };
>  
>  const
> @@ -283,6 +284,25 @@ static int qcom_cc_icc_register(struct device *dev,
>  						     desc->num_icc_hws, icd);
>  }
>  
> +static int qcom_cc_pds_attach(struct device *dev, struct qcom_cc *cc)
> +{
> +	struct dev_pm_domain_attach_data pd_data = {
> +		.pd_names = 0,
> +		.num_pd_names = 0,
> +	};
> +	int ret;
> +
> +	/* Only one power-domain platform framework will hook it up */
> +	if (dev->pm_domain)
> +		return 0;
> +
> +	ret = dev_pm_domain_attach_list(dev, &pd_data, &cc->pd_list);
> +	if (ret < 0)
> +		return ret;
> +
> +	return 0;
> +}
> +
>  int qcom_cc_really_probe(struct device *dev,
>  			 const struct qcom_cc_desc *desc, struct regmap *regmap)
>  {
> @@ -299,6 +319,10 @@ int qcom_cc_really_probe(struct device *dev,
>  	if (!cc)
>  		return -ENOMEM;
>  
> +	ret = qcom_cc_pds_attach(dev, cc);
> +	if (ret)
> +		return ret;
> +
>  	reset = &cc->reset;
>  	reset->rcdev.of_node = dev->of_node;
>  	reset->rcdev.ops = &qcom_reset_ops;
> 
> -- 
> 2.45.2
>