linux-kernel - Re: [PATCH v2 1/2] bus: tegra-aconnect: use devm_clk

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Message-ID: <32ab970f-d6a3-1232-77f1-41f97cc04f9a@nvidia.com>
Date:   Wed, 27 Mar 2019 16:40:15 +0530
From:   Sameer Pujar <spujar@...dia.com>
To:     <treding@...dia.com>, <jonathanh@...dia.com>
CC:     <linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/2] bus: tegra-aconnect: use devm_clk_*() helpers

Hi Reviewers,

Request for review and approval.

Thanks,
Sameer.

On 3/13/2019 10:11 AM, Sameer Pujar wrote:
> aconnect bus driver is using pm_clk_*() interface for managing clocks.
> With this, clocks seem to be always ON. This happens on Tegra devices
> which use BPMP co-processor to manage clock resources, where clocks
> are enabled during prepare phase. This is necessary because calls to
> BPMP are always blocking. When pm_clk_*() interface is used on such
> Tegra devices, clock prepare count is not balanced till driver remove()
> gets executed and hence clocks are seen ON always. Thus this patch
> replaces pm_clk_*() with devm_clk_*() framework.
>
> Suggested-by: Mohan Kumar D <mkumard@...dia.com>
> Reviewed-by: Jonathan Hunter <jonathanh@...dia.com>
> Signed-off-by: Sameer Pujar <spujar@...dia.com>
> ---
>   drivers/bus/tegra-aconnect.c | 64 ++++++++++++++++++++++++++++++--------------
>   1 file changed, 44 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/bus/tegra-aconnect.c b/drivers/bus/tegra-aconnect.c
> index 084ae28..9349157 100644
> --- a/drivers/bus/tegra-aconnect.c
> +++ b/drivers/bus/tegra-aconnect.c
> @@ -12,28 +12,38 @@
>   #include <linux/module.h>
>   #include <linux/of_platform.h>
>   #include <linux/platform_device.h>
> -#include <linux/pm_clock.h>
>   #include <linux/pm_runtime.h>
>   
> +struct tegra_aconnect {
> +	struct clk	*ape_clk;
> +	struct clk	*apb2ape_clk;
> +};
> +
>   static int tegra_aconnect_probe(struct platform_device *pdev)
>   {
> -	int ret;
> +	struct tegra_aconnect *aconnect;
>   
>   	if (!pdev->dev.of_node)
>   		return -EINVAL;
>   
> -	ret = pm_clk_create(&pdev->dev);
> -	if (ret)
> -		return ret;
> +	aconnect = devm_kzalloc(&pdev->dev, sizeof(struct tegra_aconnect),
> +				GFP_KERNEL);
> +	if (!aconnect)
> +		return -ENOMEM;
>   
> -	ret = of_pm_clk_add_clk(&pdev->dev, "ape");
> -	if (ret)
> -		goto clk_destroy;
> +	aconnect->ape_clk = devm_clk_get(&pdev->dev, "ape");
> +	if (IS_ERR(aconnect->ape_clk)) {
> +		dev_err(&pdev->dev, "Can't retrieve ape clock\n");
> +		return PTR_ERR(aconnect->ape_clk);
> +	}
>   
> -	ret = of_pm_clk_add_clk(&pdev->dev, "apb2ape");
> -	if (ret)
> -		goto clk_destroy;
> +	aconnect->apb2ape_clk = devm_clk_get(&pdev->dev, "apb2ape");
> +	if (IS_ERR(aconnect->apb2ape_clk)) {
> +		dev_err(&pdev->dev, "Can't retrieve apb2ape clock\n");
> +		return PTR_ERR(aconnect->apb2ape_clk);
> +	}
>   
> +	dev_set_drvdata(&pdev->dev, aconnect);
>   	pm_runtime_enable(&pdev->dev);
>   
>   	of_platform_populate(pdev->dev.of_node, NULL, NULL, &pdev->dev);
> @@ -41,30 +51,44 @@ static int tegra_aconnect_probe(struct platform_device *pdev)
>   	dev_info(&pdev->dev, "Tegra ACONNECT bus registered\n");
>   
>   	return 0;
> -
> -clk_destroy:
> -	pm_clk_destroy(&pdev->dev);
> -
> -	return ret;
>   }
>   
>   static int tegra_aconnect_remove(struct platform_device *pdev)
>   {
>   	pm_runtime_disable(&pdev->dev);
>   
> -	pm_clk_destroy(&pdev->dev);
> -
>   	return 0;
>   }
>   
>   static int tegra_aconnect_runtime_resume(struct device *dev)
>   {
> -	return pm_clk_resume(dev);
> +	struct tegra_aconnect *aconnect = dev_get_drvdata(dev);
> +	int ret;
> +
> +	ret = clk_prepare_enable(aconnect->ape_clk);
> +	if (ret) {
> +		dev_err(dev, "ape clk_enable failed: %d\n", ret);
> +		return ret;
> +	}
> +
> +	ret = clk_prepare_enable(aconnect->apb2ape_clk);
> +	if (ret) {
> +		clk_disable_unprepare(aconnect->ape_clk);
> +		dev_err(dev, "apb2ape clk_enable failed: %d\n", ret);
> +		return ret;
> +	}
> +
> +	return 0;
>   }
>   
>   static int tegra_aconnect_runtime_suspend(struct device *dev)
>   {
> -	return pm_clk_suspend(dev);
> +	struct tegra_aconnect *aconnect = dev_get_drvdata(dev);
> +
> +	clk_disable_unprepare(aconnect->ape_clk);
> +	clk_disable_unprepare(aconnect->apb2ape_clk);
> +
> +	return 0;
>   }
>   
>   static const struct dev_pm_ops tegra_aconnect_pm_ops = {