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

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Date:   Thu, 30 Aug 2018 18:06:16 +0300
From:   Aapo Vienamo <avienamo@...dia.com>
To:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Mikko Perttunen <mperttunen@...dia.com>,
        Stefan Agner <stefan@...er.ch>
CC:     <devicetree@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-mmc@...r.kernel.org>,
        Aapo Vienamo <avienamo@...dia.com>
Subject: [PATCH v3 15/38] mmc: tegra: Disable card clock during pad calibration

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

Signed-off-by: Aapo Vienamo <avienamo@...dia.com>
Acked-by: Thierry Reding <treding@...dia.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