mmc: mmci: stm32: Check when the voltage switch procedure should be done

[ Upstream commit d8e193f ]

If the card has not been power cycled, it may still be using 1.8V
signaling. This situation is detected in mmc_sd_init_card function and
should be handled in mmci stm32 variant.  The host->pwr_reg variable is
also correctly protected with spin locks.

Fixes: 94b94a9 ("mmc: mmci_sdmmc: Implement signal voltage callbacks")
Signed-off-by: Christophe Kerello <christophe.kerello@foss.st.com>
Signed-off-by: Yann Gautier <yann.gautier@foss.st.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210701143353.13188-1-yann.gautier@foss.st.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/mmc/host/mmci_stm32_sdmmc.c

@@ -479,8 +479,9 @@ static int sdmmc_post_sig_volt_switch(struct mmci_host *host,
 	u32 status;
 	int ret = 0;
 
-	if (ios->signal_voltage == MMC_SIGNAL_VOLTAGE_180) {
-		spin_lock_irqsave(&host->lock, flags);
+	spin_lock_irqsave(&host->lock, flags);
+	if (ios->signal_voltage == MMC_SIGNAL_VOLTAGE_180 &&
+	    host->pwr_reg & MCI_STM32_VSWITCHEN) {
 		mmci_write_pwrreg(host, host->pwr_reg | MCI_STM32_VSWITCH);
 		spin_unlock_irqrestore(&host->lock, flags);
 
@@ -492,9 +493,11 @@ static int sdmmc_post_sig_volt_switch(struct mmci_host *host,
 
 		writel_relaxed(MCI_STM32_VSWENDC | MCI_STM32_CKSTOPC,
 			       host->base + MMCICLEAR);
+		spin_lock_irqsave(&host->lock, flags);
 		mmci_write_pwrreg(host, host->pwr_reg &
 				  ~(MCI_STM32_VSWITCHEN | MCI_STM32_VSWITCH));
 	}
+	spin_unlock_irqrestore(&host->lock, flags);
 
 	return ret;
 }