linux-kernel - Re: [PATCH 04/10] mmc: tegra: Disable card clock during pad calibration

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Date:   Wed, 25 Jul 2018 10:14:54 +0300
From:   Mikko Perttunen <cyndis@...si.fi>
To:     Aapo Vienamo <avienamo@...dia.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Mikko Perttunen <mperttunen@...dia.com>
Cc:     linux-mmc@...r.kernel.org, devicetree@...r.kernel.org,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 04/10] mmc: tegra: Disable card clock during pad
 calibration

On 24.07.2018 17:34, Aapo Vienamo wrote:
> Disable the card clock during automatic pad drive strength calibration
> and re-enable it aftewards.

s/aftewards/afterwards/.

> 
> Signed-off-by: Aapo Vienamo <avienamo@...dia.com>
> ---
>   drivers/mmc/host/sdhci-tegra.c | 27 +++++++++++++++++++++++++++
>   1 file changed, 27 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci-tegra.c b/drivers/mmc/host/sdhci-tegra.c
> index 61067b7..0de74f4 100644
> --- a/drivers/mmc/host/sdhci-tegra.c
> +++ b/drivers/mmc/host/sdhci-tegra.c
> @@ -52,6 +52,7 @@
>   #define SDHCI_TEGRA_SDMEM_COMP_PADCTRL			0x1e0
>   #define SDHCI_TEGRA_SDMEM_COMP_PADCTRL_VREF_SEL_MASK	0x0000000f
>   #define SDHCI_TEGRA_SDMEM_COMP_PADCTRL_VREF_SEL_VAL	0x7
> +#define SDHCI_TEGRA_PAD_E_INPUT_OR_E_PWRD		BIT(31)

Looks like this should be in the previous patch.

>   
>   #define SDHCI_TEGRA_AUTO_CAL_STATUS     0x1ec
>   #define SDHCI_TEGRA_AUTO_CAL_ACTIVE     BIT(31)
> @@ -226,11 +227,35 @@ static void tegra_sdhci_configure_cal_pad(struct sdhci_host *host, bool enable)
>   	udelay(1);
>   }
>   
> +static bool tegra_sdhci_configure_card_clk(struct sdhci_host *host, bool enable)
> +{
> +	bool orig_enabled;
> +	u32 reg;
> +
> +	reg = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> +	orig_enabled = reg & SDHCI_CLOCK_CARD_EN;

I would do !!(reg & SDHCI_CLOCK_CARD_EN) here.

> +
> +	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)
>   {
>   	unsigned timeout = 10;
> +	bool card_clk_enabled;
>   	u32 reg;
>   
> +	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);
> @@ -248,6 +273,8 @@ 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 (timeout == 0)
>   		dev_err(mmc_dev(host->mmc), "Pad autocal timed out\n");
>   }
>