commit 8974ff1a60365dedf1192632f5e0c21680d49dbc
author Haibo Chen <haibo.chen@nxp.com> Mon Mar 22 18:55:38 2021 +0800
committer Stefano Babic <sbabic@denx.de> Thu Apr 08 23:59:50 2021 +0200
tree 78697d9c59fa301bb4dc77b0e228eed1e2f9b3bf
parent 1e595a81d9bc0d6fd30e3ba17e3f8a9278a381f8

mmc: fsl_esdhc_imx: add extra delay for IO voltage switch if necessary

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@nxp.com>

arch/arm/dts/imx8mm-evk-u-boot.dtsi

diff --git a/arch/arm/dts/imx8mm-evk-u-boot.dtsi b/arch/arm/dts/imx8mm-evk-u-boot.dtsi
index 495bef3..3701557 100644
--- a/arch/arm/dts/imx8mm-evk-u-boot.dtsi
+++ b/arch/arm/dts/imx8mm-evk-u-boot.dtsi
@@ -113,6 +113,7 @@
 	u-boot,dm-spl;
 	sd-uhs-sdr104;
 	sd-uhs-ddr50;
+	fsl,signal-voltage-switch-extra-delay-ms = <8>;
 };
 
 &usdhc3 {

drivers/mmc/fsl_esdhc_imx.c

diff --git a/drivers/mmc/fsl_esdhc_imx.c b/drivers/mmc/fsl_esdhc_imx.c
index 93fd934..a467583 100644
--- a/drivers/mmc/fsl_esdhc_imx.c
+++ b/drivers/mmc/fsl_esdhc_imx.c
@@ -146,6 +146,7 @@
  * @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 @@
 	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 @@
 		}
 #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 @@
 	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;