[PATCH 3/4] mmc: dw_mmc: Allow use of in-spec voltage range for vqmmc-supply

[Jonas Karlman]

The Rockchip RK3399 SoC SDMMC IO domain supports 1.8V and 3.0V mode, and
the 3.0V mode is within SD Standards allowed 2.7V-3.6V range. However,
the commit 0b75109b6aaf ("mmc: dw_mmc: return error for invalid voltage
setting") help enforce strict 1.8V and 3.3V when setting vqmmc-supply
making mmc_set_signal_voltage() now fail for MMC_SIGNAL_VOLTAGE_330 and
leading to an improper switch to MMC_SIGNAL_VOLTAGE_180.

Use regulator_set_value_clamp() to set an SD Standards voltage range,
1.70V-1.95V and 2.7V-3.6V, I/O voltage instead of requiring an exact
regulator value to closer match Linux and to fix use of 3.3V signal
voltage on Rockchip RK3399 boards using MMC_IO_VOLTAGE=y.

Fixes: 0b75109b6aaf ("mmc: dw_mmc: return error for invalid voltage setting")
Signed-off-by: Jonas Karlman <jonas at kwiboo.se>
---
 drivers/mmc/dw_mmc.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/dw_mmc.c b/drivers/mmc/dw_mmc.c
index d9c05b223d5f..c2424d7875ca 100644
--- a/drivers/mmc/dw_mmc.c
+++ b/drivers/mmc/dw_mmc.c
@@ -645,9 +645,11 @@ static int dwmci_set_ios(struct mmc *mmc)
 		int ret;
 
 		if (mmc->signal_voltage == MMC_SIGNAL_VOLTAGE_180)
-			ret = regulator_set_value(mmc->vqmmc_supply, 1800000);
+			ret = regulator_set_value_clamp(mmc->vqmmc_supply,
+							1700000, 1800000, 1950000);
 		else
-			ret = regulator_set_value(mmc->vqmmc_supply, 3300000);
+			ret = regulator_set_value_clamp(mmc->vqmmc_supply,
+							2700000, 3300000, 3600000);
 		if (ret && ret != -ENOSYS)
 			return ret;
 	}
-- 
2.54.0