linux-kernel - [PATCH] mmc: mmci: stm32: check when the voltage switch procedure should be done

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Date:   Thu, 1 Jul 2021 16:33:53 +0200
From:   Yann Gautier <yann.gautier@...s.st.com>
To:     Ulf Hansson <ulf.hansson@...aro.org>
CC:     Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Christophe Kerello <christophe.kerello@...s.st.com>,
        Yann Gautier <yann.gautier@...s.st.com>,
        <linux-mmc@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH] mmc: mmci: stm32: check when the voltage switch procedure should be done

From: Christophe Kerello <christophe.kerello@...s.st.com>

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: 94b94a93e355 ("mmc: mmci_sdmmc: Implement signal voltage callbacks")

Signed-off-by: Christophe Kerello <christophe.kerello@...s.st.com>
Signed-off-by: Yann Gautier <yann.gautier@...s.st.com>
---
 drivers/mmc/host/mmci_stm32_sdmmc.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/host/mmci_stm32_sdmmc.c b/drivers/mmc/host/mmci_stm32_sdmmc.c
index 51db30acf4dc..fdaa11f92fe6 100644
--- a/drivers/mmc/host/mmci_stm32_sdmmc.c
+++ b/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;
 }
-- 
2.17.1