mmc: disable UHS modes if Vcc cannot be switched on and off

If a power cycle cannot be done on Vcc, it is safer not to try the UHS
modes because we wouldn't be able to recover from an error occurring
during the UHS initialization.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>

drivers/mmc/mmc.c

@@ -1451,7 +1451,7 @@ static int sd_select_mode_and_width(struct mmc *mmc)
 	if (err)
 		return err;
 	/* Restrict card's capabilities by what the host can do */
-	caps = mmc->card_caps & (mmc->cfg->host_caps | MMC_MODE_1BIT);
+	caps = mmc->card_caps & (mmc->host_caps | MMC_MODE_1BIT);
 
 	if (!uhs_en)
 		caps &= ~UHS_CAPS;
@@ -1599,7 +1599,7 @@ static int mmc_select_mode_and_width(struct mmc *mmc)
 		return err;
 
 	/* Restrict card's capabilities by what the host can do */
-	mmc->card_caps &= (mmc->cfg->host_caps | MMC_MODE_1BIT);
+	mmc->card_caps &= (mmc->host_caps | MMC_MODE_1BIT);
 
 	/* Only version 4 of MMC supports wider bus widths */
 	if (mmc->version < MMC_VERSION_4)
@@ -2182,6 +2182,8 @@ int mmc_start_init(struct mmc *mmc)
 	bool uhs_en = supports_uhs(mmc->cfg->host_caps);
 	int err;
 
+	mmc->host_caps = mmc->cfg->host_caps;
+
 	/* we pretend there's no card when init is NULL */
 	no_card = mmc_getcd(mmc) == 0;
 #if !CONFIG_IS_ENABLED(DM_MMC)
@@ -2205,7 +2207,18 @@ int mmc_start_init(struct mmc *mmc)
 	if (err)
 		return err;
 
-	err = mmc_power_on(mmc);
+	err = mmc_power_cycle(mmc);
+	if (err) {
+		/*
+		 * if power cycling is not supported, we should not try
+		 * to use the UHS modes, because we wouldn't be able to
+		 * recover from an error during the UHS initialization.
+		 */
+		debug("Unable to do a full power cycle. Disabling the UHS modes for safety\n");
+		uhs_en = false;
+		mmc->host_caps &= ~UHS_CAPS;
+		err = mmc_power_on(mmc);
+	}
 	if (err)
 		return err;
 

include/mmc.h

@@ -544,6 +544,7 @@ struct mmc {
 	uint clock;
 	enum mmc_voltage signal_voltage;
 	uint card_caps;
+	uint host_caps;
 	uint ocr;
 	uint dsr;
 	uint dsr_imp;