[PATCH 2/2] mmc: fsl_esdhc_imx: add extra delay for IO voltage switch if necessary

[haibo.chen at nxp.com]

From: Haibo Chen <haibo.chen at nxp.com>

Some board like imx8mm-evkb, IO voltage switch from 3.3v to 1.8v need
around 18ms, common code only delay 10ms, so need to delay extra 8ms.
Otherwise voltage switch will timeout when wait for data0 line.

This IO voltage switch time depends on board design, depend on the
PMIC and capacitance. imx8mm-evkb board use PCA9450(PMIC) and 10uF
capacitance.

Signed-off-by: Haibo Chen <haibo.chen at nxp.com>
---
 arch/arm/dts/imx8mm-evk-u-boot.dtsi |  1 +
 drivers/mmc/fsl_esdhc_imx.c         | 12 ++++++++++++
 2 files changed, 13 insertions(+)

diff --git a/arch/arm/dts/imx8mm-evk-u-boot.dtsi b/arch/arm/dts/imx8mm-evk-u-boot.dtsi
index e843a5648e..bccf4fe947 100644
--- a/arch/arm/dts/imx8mm-evk-u-boot.dtsi
+++ b/arch/arm/dts/imx8mm-evk-u-boot.dtsi
@@ -102,6 +102,7 @@
 	u-boot,dm-spl;
 	sd-uhs-sdr104;
 	sd-uhs-ddr50;
+	fsl,signal-voltage-switch-extra-delay-ms = <8>;
 };
 
 &usdhc3 {
diff --git a/drivers/mmc/fsl_esdhc_imx.c b/drivers/mmc/fsl_esdhc_imx.c
index 722f33c68c..ef2b71e6b7 100644
--- a/drivers/mmc/fsl_esdhc_imx.c
+++ b/drivers/mmc/fsl_esdhc_imx.c
@@ -146,6 +146,7 @@ struct esdhc_soc_data {
  * @start_tuning_tap: the start point for tuning in tuning_ctrl register
  * @strobe_dll_delay_target: settings in strobe_dllctrl
  * @signal_voltage: indicating the current voltage
+ * @signal_voltage_switch_extra_delay_ms: extra delay for IO voltage switch
  * @cd_gpio: gpio for card detection
  * @wp_gpio: gpio for write protection
  */
@@ -170,6 +171,7 @@ struct fsl_esdhc_priv {
 	u32 tuning_start_tap;
 	u32 strobe_dll_delay_target;
 	u32 signal_voltage;
+	u32 signal_voltage_switch_extra_delay_ms;
 #if CONFIG_IS_ENABLED(DM_REGULATOR)
 	struct udevice *vqmmc_dev;
 	struct udevice *vmmc_dev;
@@ -836,6 +838,14 @@ static int esdhc_set_voltage(struct mmc *mmc)
 		}
 #endif
 		esdhc_setbits32(&regs->vendorspec, ESDHC_VENDORSPEC_VSELECT);
+		/*
+		 * some board like imx8mm-evk need about 18ms to switch
+		 * the IO voltage from 3.3v to 1.8v, common code only
+		 * delay 10ms, so need to delay extra time to make sure
+		 * the IO voltage change to 1.8v.
+		 */
+		if (priv->signal_voltage_switch_extra_delay_ms)
+			mdelay(priv->signal_voltage_switch_extra_delay_ms);
 		if (esdhc_read32(&regs->vendorspec) & ESDHC_VENDORSPEC_VSELECT)
 			return 0;
 
@@ -1450,6 +1460,8 @@ static int fsl_esdhc_of_to_plat(struct udevice *dev)
 	val = fdtdec_get_int(fdt, node, "fsl,strobe-dll-delay-target",
 			     ESDHC_STROBE_DLL_CTRL_SLV_DLY_TARGET_DEFAULT);
 	priv->strobe_dll_delay_target = val;
+	val = fdtdec_get_int(fdt, node, "fsl,signal-voltage-switch-extra-delay-ms", 0);
+	priv->signal_voltage_switch_extra_delay_ms = val;
 
 	if (dev_read_bool(dev, "broken-cd"))
 		priv->broken_cd = 1;
-- 
2.17.1