linux-kernel - Re: [PATCH v2 2/4] mmc: sdhci-of-arasan: Control clock for accessing syscon

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Message-ID: <e1ed95dc-ae81-d603-fde3-06db12c12a07@rock-chips.com>
Date:   Wed, 31 Aug 2016 11:11:01 +0800
From:   Ziyuan Xu <xzy.xu@...k-chips.com>
To:     Shawn Lin <shawn.lin@...k-chips.com>,
        Heiko Stuebner <heiko@...ech.de>,
        Rob Herring <robh+dt@...nel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>
Cc:     Adrian Hunter <adrian.hunter@...el.com>, linux-mmc@...r.kernel.org,
        devicetree@...r.kernel.org, linux-rockchip@...ts.infradead.org,
        Douglas Anderson <dianders@...omium.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/4] mmc: sdhci-of-arasan: Control clock for accessing
 syscon

Hi Shawn,


On 2016年08月31日 09:37, Shawn Lin wrote:
> In the eariler commit 65820199272d ("Documentation: mmc:
> sdhci-of-arasan: Add soc-ctl-syscon for corecfg regs"), we
> introduced syscon to control corecfg_* stuff provided by
> arasan. But given that we may need to ungate the clock for
> accessing corecfg_*, it not so perfect as it depends on
> whether specific clock driver disables it if not referenced.
> Meanwhile, if we don't need arasan contoller to work anymore,
> there is no reason to still enable it. So let's control this
> clock when needed.
>
> Signed-off-by: Shawn Lin <shawn.lin@...k-chips.com>
>
> ---

Without  this series of patches, we can't gate aclk_emmcgrf even though 
driver enter suspend/remove. It meaningful to save power consumption.
It looks nice to me, and also I have tested on rk3399 board, so

Tested-by: Ziyuan Xu <xzy.xu@...k-chips.com>

>
> Changes in v2:
> - assign NULL to clk_syscon if it's not deferral error.
>
>   drivers/mmc/host/sdhci-of-arasan.c | 33 ++++++++++++++++++++++++++++++---
>   1 file changed, 30 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci-of-arasan.c b/drivers/mmc/host/sdhci-of-arasan.c
> index 0b3a9cf..3169f81 100644
> --- a/drivers/mmc/host/sdhci-of-arasan.c
> +++ b/drivers/mmc/host/sdhci-of-arasan.c
> @@ -78,6 +78,7 @@ struct sdhci_arasan_soc_ctl_map {
>    * struct sdhci_arasan_data
>    * @host:		Pointer to the main SDHCI host structure.
>    * @clk_ahb:		Pointer to the AHB clock
> + * @clk_syscon:		Pointer to the optional clock for accessing syscon
>    * @phy:		Pointer to the generic phy
>    * @is_phy_on:		True if the PHY is on; false if not.
>    * @sdcardclk_hw:	Struct for the clock we might provide to a PHY.
> @@ -88,6 +89,7 @@ struct sdhci_arasan_soc_ctl_map {
>   struct sdhci_arasan_data {
>   	struct sdhci_host *host;
>   	struct clk	*clk_ahb;
> +	struct clk	*clk_syscon;
>   	struct phy	*phy;
>   	bool		is_phy_on;
>   
> @@ -290,6 +292,7 @@ static int sdhci_arasan_suspend(struct device *dev)
>   
>   	clk_disable(pltfm_host->clk);
>   	clk_disable(sdhci_arasan->clk_ahb);
> +	clk_disable(sdhci_arasan->clk_syscon);
>   
>   	return 0;
>   }
> @@ -309,6 +312,12 @@ static int sdhci_arasan_resume(struct device *dev)
>   	struct sdhci_arasan_data *sdhci_arasan = sdhci_pltfm_priv(pltfm_host);
>   	int ret;
>   
> +	ret = clk_enable(sdhci_arasan->clk_syscon);
> +	if (ret) {
> +		dev_err(dev, "Cannot enable syscon clock.\n");
> +		return ret;
> +	}
> +
>   	ret = clk_enable(sdhci_arasan->clk_ahb);
>   	if (ret) {
>   		dev_err(dev, "Cannot enable AHB clock.\n");
> @@ -528,26 +537,41 @@ static int sdhci_arasan_probe(struct platform_device *pdev)
>   					ret);
>   			goto err_pltfm_free;
>   		}
> +
> +		sdhci_arasan->clk_syscon = devm_clk_get(&pdev->dev,
> +							"clk_syscon");
> +		if (IS_ERR(sdhci_arasan->clk_syscon)) {
> +			ret = PTR_ERR(sdhci_arasan->clk_syscon);
> +			if (ret == -EPROBE_DEFER)
> +				goto err_pltfm_free;
> +			else
> +				sdhci_arasan->clk_syscon = NULL;
> +		}
> +
> +		if (clk_prepare_enable(sdhci_arasan->clk_syscon)) {
> +			dev_err(&pdev->dev, "Unable to enable syscon clock.\n");
> +			goto err_pltfm_free;
> +		}
>   	}
>   
>   	sdhci_arasan->clk_ahb = devm_clk_get(&pdev->dev, "clk_ahb");
>   	if (IS_ERR(sdhci_arasan->clk_ahb)) {
>   		dev_err(&pdev->dev, "clk_ahb clock not found.\n");
>   		ret = PTR_ERR(sdhci_arasan->clk_ahb);
> -		goto err_pltfm_free;
> +		goto clk_dis_syscon;
>   	}
>   
>   	clk_xin = devm_clk_get(&pdev->dev, "clk_xin");
>   	if (IS_ERR(clk_xin)) {
>   		dev_err(&pdev->dev, "clk_xin clock not found.\n");
>   		ret = PTR_ERR(clk_xin);
> -		goto err_pltfm_free;
> +		goto clk_dis_syscon;
>   	}
>   
>   	ret = clk_prepare_enable(sdhci_arasan->clk_ahb);
>   	if (ret) {
>   		dev_err(&pdev->dev, "Unable to enable AHB clock.\n");
> -		goto err_pltfm_free;
> +		goto clk_dis_syscon;
>   	}
>   
>   	ret = clk_prepare_enable(clk_xin);
> @@ -607,6 +631,8 @@ clk_disable_all:
>   	clk_disable_unprepare(clk_xin);
>   clk_dis_ahb:
>   	clk_disable_unprepare(sdhci_arasan->clk_ahb);
> +clk_dis_syscon:
> +	clk_disable_unprepare(sdhci_arasan->clk_syscon);
>   err_pltfm_free:
>   	sdhci_pltfm_free(pdev);
>   	return ret;
> @@ -631,6 +657,7 @@ static int sdhci_arasan_remove(struct platform_device *pdev)
>   	ret = sdhci_pltfm_unregister(pdev);
>   
>   	clk_disable_unprepare(clk_ahb);
> +	clk_disable_unprepare(sdhci_arasan->clk_syscon);
>   
>   	return ret;
>   }