Commit 212b0cf1 authored by Aapo Vienamo's avatar Aapo Vienamo Committed by Ulf Hansson
Browse files

mmc: tegra: Power on the calibration pad 



Automatic pad drive strength calibration is performed on a separate pad
identical to the ones used for driving the actual bus. Power on the
calibration pad during the calibration procedure and power it off
afterwards to save power.

Signed-off-by: default avatarAapo Vienamo <avienamo@nvidia.com>
Reviewed-by: default avatarMikko Perttunen <mperttunen@nvidia.com>
Acked-by: default avatarThierry Reding <treding@nvidia.com>
Acked-by: default avatarAdrian Hunter <adrian.hunter@intel.com>
Signed-off-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
parent 9d548f11

drivers/mmc/host/sdhci-tegra.c

+26 −0
Original line number Diff line number Diff line
@@ -54,6 +54,7 @@ 
#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_SDMEM_COMP_PADCTRL_E_INPUT_E_PWRD	BIT(31)



#define SDHCI_TEGRA_AUTO_CAL_STATUS			0x1ec

#define SDHCI_TEGRA_AUTO_CAL_ACTIVE			BIT(31)
@@ -238,11 +239,34 @@ static void tegra_sdhci_reset(struct sdhci_host *host, u8 mask) 
	tegra_host->ddr_signaling = false;

}



static void tegra_sdhci_configure_cal_pad(struct sdhci_host *host, bool enable)

{

	u32 val;



	/*

	 * Enable or disable the additional I/O pad used by the drive strength

	 * calibration process.

	 */

	val = sdhci_readl(host, SDHCI_TEGRA_SDMEM_COMP_PADCTRL);



	if (enable)

		val |= SDHCI_TEGRA_SDMEM_COMP_PADCTRL_E_INPUT_E_PWRD;

	else

		val &= ~SDHCI_TEGRA_SDMEM_COMP_PADCTRL_E_INPUT_E_PWRD;



	sdhci_writel(host, val, SDHCI_TEGRA_SDMEM_COMP_PADCTRL);



	if (enable)

		usleep_range(1, 2);

}



static void tegra_sdhci_pad_autocalib(struct sdhci_host *host)

{

	u32 reg;

	int ret;



	tegra_sdhci_configure_cal_pad(host, true);



	reg = sdhci_readl(host, SDHCI_TEGRA_AUTO_CAL_CONFIG);

	reg |= SDHCI_AUTO_CAL_ENABLE | SDHCI_AUTO_CAL_START;

	sdhci_writel(host, reg, SDHCI_TEGRA_AUTO_CAL_CONFIG);
@@ -253,6 +277,8 @@ static void tegra_sdhci_pad_autocalib(struct sdhci_host *host) 
				 reg, !(reg & SDHCI_TEGRA_AUTO_CAL_ACTIVE),

				 1000, 10000);



	tegra_sdhci_configure_cal_pad(host, false);



	if (ret)

		dev_err(mmc_dev(host->mmc), "Pad autocal timed out\n");

}

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