[PATCH v2 04/10] mmc: tegra: Disable card clock during pad calibration

[Aapo Vienamo <avienamo@nvidia.com>]

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

Signed-off-by: Aapo Vienamo <avienamo@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 363490e..79ecdd0 100644
--- a/drivers/mmc/host/sdhci-tegra.c
+++ b/drivers/mmc/host/sdhci-tegra.c
@@ -259,11 +259,35 @@ 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);
+
+	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)
 {
+	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);
@@ -277,6 +301,8 @@ 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");
 }
-- 
2.7.4