linux-kernel - Re: [PATCH 7/8] clk: qcom: gcc-sm8150: use runtime PM for the clock controller

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Date:   Mon, 31 Jan 2022 18:01:53 -0600
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Bhupesh Sharma <bhupesh.sharma@...aro.org>
Cc:     linux-arm-msm@...r.kernel.org, bhupesh.linux@...il.com,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        robh+dt@...nel.org, agross@...nel.org, sboyd@...nel.org,
        tdas@...eaurora.org, mturquette@...libre.com,
        linux-clk@...r.kernel.org, davem@...emloft.net,
        netdev@...r.kernel.org
Subject: Re: [PATCH 7/8] clk: qcom: gcc-sm8150: use runtime PM for the clock
 controller

On Wed 26 Jan 16:17 CST 2022, Bhupesh Sharma wrote:

> On sm8150 emac clk registers are powered up by the GDSC power
> domain. Use runtime PM calls to make sure that required power domain is
> powered on while we access clock controller's registers.
> 

Typically the GCC registers need only "cx" enabled for us to much around
with its registers and I don't see you add any references to additional
resources, so can you please elaborate on how this affects the state of
the system to enable you to operate the emac registers?

Regards,
Bjorn

> Cc: Stephen Boyd <sboyd@...nel.org>
> Signed-off-by: Bhupesh Sharma <bhupesh.sharma@...aro.org>
> ---
>  drivers/clk/qcom/gcc-sm8150.c | 27 +++++++++++++++++++++++++--
>  1 file changed, 25 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/clk/qcom/gcc-sm8150.c b/drivers/clk/qcom/gcc-sm8150.c
> index ada755ad55f7..2e71afed81fd 100644
> --- a/drivers/clk/qcom/gcc-sm8150.c
> +++ b/drivers/clk/qcom/gcc-sm8150.c
> @@ -5,6 +5,7 @@
>  #include <linux/bitops.h>
>  #include <linux/err.h>
>  #include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
>  #include <linux/of_device.h>
> @@ -3792,19 +3793,41 @@ static const struct of_device_id gcc_sm8150_match_table[] = {
>  };
>  MODULE_DEVICE_TABLE(of, gcc_sm8150_match_table);
>  
> +static void gcc_sm8150_pm_runtime_disable(void *data)
> +{
> +	pm_runtime_disable(data);
> +}
> +
>  static int gcc_sm8150_probe(struct platform_device *pdev)
>  {
>  	struct regmap *regmap;
> +	int ret;
> +
> +	pm_runtime_enable(&pdev->dev);
> +
> +	ret = devm_add_action_or_reset(&pdev->dev, gcc_sm8150_pm_runtime_disable, &pdev->dev);
> +	if (ret)
> +		return ret;
> +
> +	ret = pm_runtime_resume_and_get(&pdev->dev);
> +	if (ret)
> +		return ret;
>  
>  	regmap = qcom_cc_map(pdev, &gcc_sm8150_desc);
> -	if (IS_ERR(regmap))
> +	if (IS_ERR(regmap)) {
> +		pm_runtime_put(&pdev->dev);
>  		return PTR_ERR(regmap);
> +	}
>  
>  	/* Disable the GPLL0 active input to NPU and GPU via MISC registers */
>  	regmap_update_bits(regmap, 0x4d110, 0x3, 0x3);
>  	regmap_update_bits(regmap, 0x71028, 0x3, 0x3);
>  
> -	return qcom_cc_really_probe(pdev, &gcc_sm8150_desc, regmap);
> +	ret = qcom_cc_really_probe(pdev, &gcc_sm8150_desc, regmap);
> +
> +	pm_runtime_put(&pdev->dev);
> +
> +	return ret;
>  }
>  
>  static struct platform_driver gcc_sm8150_driver = {
> -- 
> 2.34.1
>