mmc: sdhci: Use regulator min/max voltage range according to spec

For regulator vmmc/vmmcq, use voltage range as below
3.3v/3.0v: (2.7v, 3.6v)
1.8v: (1.7v, 1.95v)
Original code uses the precise value which may fail in regulator
driver if it does NOT support the precise voltage.

Signed-off-by: Jialing Fu <jlfu@marvell.com>
Signed-off-by: Kevin Liu <kliu5@marvell.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/host/sdhci.c

@@ -1618,7 +1618,7 @@ static int sdhci_do_3_3v_signal_voltage_switch(struct sdhci_host *host,
 	sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
 
 	if (host->vqmmc) {
-		ret = regulator_set_voltage(host->vqmmc, 3300000, 3300000);
+		ret = regulator_set_voltage(host->vqmmc, 2700000, 3600000);
 		if (ret) {
 			pr_warning("%s: Switching to 3.3V signalling voltage "
 				   " failed\n", mmc_hostname(host->mmc));
@@ -1662,7 +1662,7 @@ static int sdhci_do_1_8v_signal_voltage_switch(struct sdhci_host *host,
 		 */
 		if (host->vqmmc)
 			ret = regulator_set_voltage(host->vqmmc,
-				1800000, 1800000);
+				1700000, 1950000);
 		else
 			ret = 0;
 
@@ -2860,8 +2860,8 @@ int sdhci_add_host(struct sdhci_host *host)
 		}
 	} else {
 		regulator_enable(host->vqmmc);
-		if (!regulator_is_supported_voltage(host->vqmmc, 1800000,
-			1800000))
+		if (!regulator_is_supported_voltage(host->vqmmc, 1700000,
+			1950000))
 			caps[1] &= ~(SDHCI_SUPPORT_SDR104 |
 					SDHCI_SUPPORT_SDR50 |
 					SDHCI_SUPPORT_DDR50);
@@ -2925,16 +2925,14 @@ int sdhci_add_host(struct sdhci_host *host)
 
 #ifdef CONFIG_REGULATOR
 	if (host->vmmc) {
-		ret = regulator_is_supported_voltage(host->vmmc, 3300000,
-			3300000);
+		ret = regulator_is_supported_voltage(host->vmmc, 2700000,
+			3600000);
 		if ((ret <= 0) || (!(caps[0] & SDHCI_CAN_VDD_330)))
 			caps[0] &= ~SDHCI_CAN_VDD_330;
-		ret = regulator_is_supported_voltage(host->vmmc, 3000000,
-			3000000);
 		if ((ret <= 0) || (!(caps[0] & SDHCI_CAN_VDD_300)))
 			caps[0] &= ~SDHCI_CAN_VDD_300;
-		ret = regulator_is_supported_voltage(host->vmmc, 1800000,
-			1800000);
+		ret = regulator_is_supported_voltage(host->vmmc, 1700000,
+			1950000);
 		if ((ret <= 0) || (!(caps[0] & SDHCI_CAN_VDD_180)))
 			caps[0] &= ~SDHCI_CAN_VDD_180;
 	}