linux-kernel - Re: [PATCH 16/40] mmc: tegra: Disable card clock during pad calibration

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Date:   Thu, 9 Aug 2018 14:54:22 +0200
From:   Thierry Reding <thierry.reding@...il.com>
To:     Aapo Vienamo <avienamo@...dia.com>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Mikko Perttunen <mperttunen@...dia.com>,
        Stefan Agner <stefan@...er.ch>, devicetree@...r.kernel.org,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mmc@...r.kernel.org
Subject: Re: [PATCH 16/40] mmc: tegra: Disable card clock during pad
 calibration

On Wed, Aug 01, 2018 at 07:32:06PM +0300, Aapo Vienamo wrote:
> Disable the card clock during automatic pad drive strength calibration
> and re-enable it afterwards.
> 
> Signed-off-by: Aapo Vienamo <avienamo@...dia.com>
> ---
>  drivers/mmc/host/sdhci-tegra.c | 26 ++++++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci-tegra.c b/drivers/mmc/host/sdhci-tegra.c
> index 9e22fec..c2b388b 100644
> --- a/drivers/mmc/host/sdhci-tegra.c
> +++ b/drivers/mmc/host/sdhci-tegra.c
> @@ -260,11 +260,35 @@ static void tegra_sdhci_configure_cal_pad(struct sdhci_host *host, bool enable)
>  	}
>  }
>  
> +static bool tegra_sdhci_configure_card_clk(struct sdhci_host *host, bool enable)
> +{
> +	bool orig_enabled;

I don't see a need for the orig_ prefix. If you're concerned that
"enable" and "enabled" might clash, perhaps "status" would be a better
name?

Thierry

> +	u32 reg;
> +
> +	reg = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> +	orig_enabled = !!(reg & SDHCI_CLOCK_CARD_EN);
> +
> +	if (orig_enabled == enable)
> +		return orig_enabled;
> +
> +	if (enable)
> +		reg |= SDHCI_CLOCK_CARD_EN;
> +	else
> +		reg &= ~SDHCI_CLOCK_CARD_EN;
> +
> +	sdhci_writew(host, reg, SDHCI_CLOCK_CONTROL);
> +
> +	return orig_enabled;
> +}
> +
>  static void tegra_sdhci_pad_autocalib(struct sdhci_host *host)
>  {
> +	bool card_clk_enabled;
>  	u32 reg;
>  	int ret;
>  
> +	card_clk_enabled = tegra_sdhci_configure_card_clk(host, false);
> +
>  	tegra_sdhci_configure_cal_pad(host, true);
>  
>  	reg = sdhci_readl(host, SDHCI_TEGRA_AUTO_CAL_CONFIG);
> @@ -278,6 +302,8 @@ static void tegra_sdhci_pad_autocalib(struct sdhci_host *host)
>  
>  	tegra_sdhci_configure_cal_pad(host, false);
>  
> +	tegra_sdhci_configure_card_clk(host, card_clk_enabled);
> +
>  	if (ret)
>  		dev_err(mmc_dev(host->mmc), "Pad autocal timed out\n");
>  }
> -- 
> 2.7.4
> 

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