From mboxrd@z Thu Jan 1 00:00:00 1970 From: Aapo Vienamo Subject: [PATCH v2 15/40] mmc: tegra: Power on the calibration pad Date: Fri, 10 Aug 2018 21:08:17 +0300 Message-ID: <1533924522-1037-16-git-send-email-avienamo@nvidia.com> References: <1533924522-1037-1-git-send-email-avienamo@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: In-Reply-To: <1533924522-1037-1-git-send-email-avienamo@nvidia.com> Sender: linux-kernel-owner@vger.kernel.org To: Rob Herring , Mark Rutland , Thierry Reding , Jonathan Hunter , Ulf Hansson , Adrian Hunter , Mikko Perttunen , Stefan Agner Cc: devicetree@vger.kernel.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mmc@vger.kernel.org, Aapo Vienamo List-Id: devicetree@vger.kernel.org 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 Reviewed-by: Mikko Perttunen --- 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 6ddc7c2..a00e366 100644 --- a/drivers/mmc/host/sdhci-tegra.c +++ b/drivers/mmc/host/sdhci-tegra.c @@ -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"); } -- 2.7.4