[PATCH v3 15/38] mmc: tegra: Disable card clock during pad calibration

[Aapo Vienamo]

Disable the card clock during automatic pad drive strength calibration
and re-enable it afterwards.

Signed-off-by: Aapo Vienamo <avien...@nvidia.com>
Acked-by: Thierry Reding <tred...@nvidia.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 e63cd6b2fc9f..ec07a3ce0247 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)
                usleep_range(1, 2);
 }
 
+static bool tegra_sdhci_configure_card_clk(struct sdhci_host *host, bool 
enable)
+{
+       bool status;
+       u32 reg;
+
+       reg = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
+       status = !!(reg & SDHCI_CLOCK_CARD_EN);
+
+       if (status == enable)
+               return status;
+
+       if (enable)
+               reg |= SDHCI_CLOCK_CARD_EN;
+       else
+               reg &= ~SDHCI_CLOCK_CARD_EN;
+
+       sdhci_writew(host, reg, SDHCI_CLOCK_CONTROL);
+
+       return status;
+}
+
 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);
@@ -279,6 +303,8 @@ 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");
 }
-- 
2.18.0