[PATCH v2 03/10] mmc: tegra: Power on the calibration pad
From: Aapo Vienamo <hidden>
Date: 2018-07-26 12:27:15
Also in:
linux-devicetree, linux-mmc, lkml
Subsystem:
multimedia card (mmc), secure digital (sd) and sdio subsystem, secure digital host controller interface (sdhci) driver, the rest · Maintainers:
Ulf Hansson, Adrian Hunter, Linus Torvalds
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: Aapo Vienamo <redacted> Reviewed-by: Mikko Perttunen <mperttunen@nvidia.com> --- drivers/mmc/host/sdhci-tegra.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+)
diff --git a/drivers/mmc/host/sdhci-tegra.c b/drivers/mmc/host/sdhci-tegra.c
index 51eda20..363490e 100644
--- a/drivers/mmc/host/sdhci-tegra.c
+++ b/drivers/mmc/host/sdhci-tegra.c@@ -53,6 +53,7 @@ #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)
@@ -241,11 +242,30 @@ 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 reg; + + /* + * Enable or disable the additional I/O pad used by the drive strength + * calibration process. + */ + reg = sdhci_readl(host, SDHCI_TEGRA_SDMEM_COMP_PADCTRL); + if (enable) + reg |= SDHCI_TEGRA_SDMEM_COMP_PADCTRL_E_INPUT_E_PWRD; + else + reg &= ~SDHCI_TEGRA_SDMEM_COMP_PADCTRL_E_INPUT_E_PWRD; + sdhci_writel(host, reg, SDHCI_TEGRA_SDMEM_COMP_PADCTRL); + udelay(1); +} + 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);
@@ -255,6 +275,8 @@ static void tegra_sdhci_pad_autocalib(struct sdhci_host *host) reg, !(reg & SDHCI_TEGRA_AUTO_CAL_ACTIVE), 1, 10000); + tegra_sdhci_configure_cal_pad(host, false); + if (ret) dev_err(mmc_dev(host->mmc), "Pad autocal timed out\n"); }
--
2.7.4