X-Git-Url: http://git.ipfire.org/?a=blobdiff_plain;f=drivers%2Fmmc%2Fmmc.c;h=877ce1757da38bce892e0d6c319e29d39a5e7bf9;hb=bc1e3272ff3437f7cfc5e8bf1d1f2767f6d78262;hp=664b71affd81ddee6a5ba0a17f1e9664714b1610;hpb=35f6782055c99410fbeae33ab28ea68de154360c;p=people%2Fms%2Fu-boot.git

diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index 664b71affd..877ce1757d 100644
--- a/drivers/mmc/mmc.c
+++ b/drivers/mmc/mmc.c
@@ -32,6 +32,7 @@ static const unsigned int sd_au_size[] = {
 
 static int mmc_set_signal_voltage(struct mmc *mmc, uint signal_voltage);
 static int mmc_power_cycle(struct mmc *mmc);
+static int mmc_select_mode_and_width(struct mmc *mmc, uint card_caps);
 
 #if CONFIG_IS_ENABLED(MMC_TINY)
 static struct mmc mmc_static;
@@ -57,6 +58,12 @@ struct blk_desc *mmc_get_blk_desc(struct mmc *mmc)
 #endif
 
 #if !CONFIG_IS_ENABLED(DM_MMC)
+
+static int mmc_wait_dat0(struct mmc *mmc, int state, int timeout)
+{
+	return -ENOSYS;
+}
+
 __weak int board_mmc_getwp(struct mmc *mmc)
 {
 	return -1;
@@ -272,6 +279,7 @@ int mmc_send_status(struct mmc *mmc, int timeout)
 int mmc_set_blocklen(struct mmc *mmc, int len)
 {
 	struct mmc_cmd cmd;
+	int err;
 
 	if (mmc->ddr_mode)
 		return 0;
@@ -280,7 +288,24 @@ int mmc_set_blocklen(struct mmc *mmc, int len)
 	cmd.resp_type = MMC_RSP_R1;
 	cmd.cmdarg = len;
 
-	return mmc_send_cmd(mmc, &cmd, NULL);
+	err = mmc_send_cmd(mmc, &cmd, NULL);
+
+#ifdef CONFIG_MMC_QUIRKS
+	if (err && (mmc->quirks & MMC_QUIRK_RETRY_SET_BLOCKLEN)) {
+		int retries = 4;
+		/*
+		 * It has been seen that SET_BLOCKLEN may fail on the first
+		 * attempt, let's try a few more time
+		 */
+		do {
+			err = mmc_send_cmd(mmc, &cmd, NULL);
+			if (!err)
+				break;
+		} while (retries--);
+	}
+#endif
+
+	return err;
 }
 
 static int mmc_read_blocks(struct mmc *mmc, void *dst, lbaint_t start,
@@ -402,7 +427,67 @@ static int mmc_go_idle(struct mmc *mmc)
 	return 0;
 }
 
-static int sd_send_op_cond(struct mmc *mmc)
+static int mmc_switch_voltage(struct mmc *mmc, int signal_voltage)
+{
+	struct mmc_cmd cmd;
+	int err = 0;
+
+	/*
+	 * Send CMD11 only if the request is to switch the card to
+	 * 1.8V signalling.
+	 */
+	if (signal_voltage == MMC_SIGNAL_VOLTAGE_330)
+		return mmc_set_signal_voltage(mmc, signal_voltage);
+
+	cmd.cmdidx = SD_CMD_SWITCH_UHS18V;
+	cmd.cmdarg = 0;
+	cmd.resp_type = MMC_RSP_R1;
+
+	err = mmc_send_cmd(mmc, &cmd, NULL);
+	if (err)
+		return err;
+
+	if (!mmc_host_is_spi(mmc) && (cmd.response[0] & MMC_STATUS_ERROR))
+		return -EIO;
+
+	/*
+	 * The card should drive cmd and dat[0:3] low immediately
+	 * after the response of cmd11, but wait 100 us to be sure
+	 */
+	err = mmc_wait_dat0(mmc, 0, 100);
+	if (err == -ENOSYS)
+		udelay(100);
+	else if (err)
+		return -ETIMEDOUT;
+
+	/*
+	 * During a signal voltage level switch, the clock must be gated
+	 * for 5 ms according to the SD spec
+	 */
+	mmc_set_clock(mmc, mmc->clock, true);
+
+	err = mmc_set_signal_voltage(mmc, signal_voltage);
+	if (err)
+		return err;
+
+	/* Keep clock gated for at least 10 ms, though spec only says 5 ms */
+	mdelay(10);
+	mmc_set_clock(mmc, mmc->clock, false);
+
+	/*
+	 * Failure to switch is indicated by the card holding
+	 * dat[0:3] low. Wait for at least 1 ms according to spec
+	 */
+	err = mmc_wait_dat0(mmc, 1, 1000);
+	if (err == -ENOSYS)
+		udelay(1000);
+	else if (err)
+		return -ETIMEDOUT;
+
+	return 0;
+}
+
+static int sd_send_op_cond(struct mmc *mmc, bool uhs_en)
 {
 	int timeout = 1000;
 	int err;
@@ -434,6 +519,9 @@ static int sd_send_op_cond(struct mmc *mmc)
 		if (mmc->version == SD_VERSION_2)
 			cmd.cmdarg |= OCR_HCS;
 
+		if (uhs_en)
+			cmd.cmdarg |= OCR_S18R;
+
 		err = mmc_send_cmd(mmc, &cmd, NULL);
 
 		if (err)
@@ -464,6 +552,13 @@ static int sd_send_op_cond(struct mmc *mmc)
 
 	mmc->ocr = cmd.response[0];
 
+	if (uhs_en && !(mmc_host_is_spi(mmc)) && (cmd.response[0] & 0x41000000)
+	    == 0x41000000) {
+		err = mmc_switch_voltage(mmc, MMC_SIGNAL_VOLTAGE_180);
+		if (err)
+			return err;
+	}
+
 	mmc->high_capacity = ((mmc->ocr & OCR_HCS) == OCR_HCS);
 	mmc->rca = 0;
 
@@ -621,6 +716,10 @@ static int mmc_set_card_speed(struct mmc *mmc, enum bus_mode mode)
 	case MMC_HS_52:
 	case MMC_DDR_52:
 		speed_bits = EXT_CSD_TIMING_HS;
+		break;
+	case MMC_HS_200:
+		speed_bits = EXT_CSD_TIMING_HS200;
+		break;
 	case MMC_LEGACY:
 		speed_bits = EXT_CSD_TIMING_LEGACY;
 		break;
@@ -667,9 +766,13 @@ static int mmc_get_capabilities(struct mmc *mmc)
 
 	mmc->card_caps |= MMC_MODE_4BIT | MMC_MODE_8BIT;
 
-	cardtype = ext_csd[EXT_CSD_CARD_TYPE] & 0xf;
+	cardtype = ext_csd[EXT_CSD_CARD_TYPE] & 0x3f;
+	mmc->cardtype = cardtype;
 
-	/* High Speed is set, there are two types: 52MHz and 26MHz */
+	if (cardtype & (EXT_CSD_CARD_TYPE_HS200_1_2V |
+			EXT_CSD_CARD_TYPE_HS200_1_8V)) {
+		mmc->card_caps |= MMC_MODE_HS200;
+	}
 	if (cardtype & EXT_CSD_CARD_TYPE_52) {
 		if (cardtype & EXT_CSD_CARD_TYPE_DDR_52)
 			mmc->card_caps |= MMC_MODE_DDR_52MHz;
@@ -709,10 +812,38 @@ static int mmc_set_capacity(struct mmc *mmc, int part_num)
 	return 0;
 }
 
+static int mmc_boot_part_access_chk(struct mmc *mmc, unsigned int part_num)
+{
+	int forbidden = 0;
+	bool change = false;
+
+	if (part_num & PART_ACCESS_MASK)
+		forbidden = MMC_CAP(MMC_HS_200);
+
+	if (MMC_CAP(mmc->selected_mode) & forbidden) {
+		debug("selected mode (%s) is forbidden for part %d\n",
+		      mmc_mode_name(mmc->selected_mode), part_num);
+		change = true;
+	} else if (mmc->selected_mode != mmc->best_mode) {
+		debug("selected mode is not optimal\n");
+		change = true;
+	}
+
+	if (change)
+		return mmc_select_mode_and_width(mmc,
+						 mmc->card_caps & ~forbidden);
+
+	return 0;
+}
+
 int mmc_switch_part(struct mmc *mmc, unsigned int part_num)
 {
 	int ret;
 
+	ret = mmc_boot_part_access_chk(mmc, part_num);
+	if (ret)
+		return ret;
+
 	ret = mmc_switch(mmc, EXT_CSD_CMD_SET_NORMAL, EXT_CSD_PART_CONF,
 			 (mmc->part_config & ~PART_ACCESS_MASK)
 			 | (part_num & PART_ACCESS_MASK));
@@ -970,6 +1101,7 @@ static int sd_get_capabilities(struct mmc *mmc)
 	ALLOC_CACHE_ALIGN_BUFFER(__be32, switch_status, 16);
 	struct mmc_data data;
 	int timeout;
+	u32 sd3_bus_mode;
 
 	mmc->card_caps = MMC_MODE_1BIT;
 
@@ -1051,6 +1183,22 @@ retry_scr:
 	if (__be32_to_cpu(switch_status[3]) & SD_HIGHSPEED_SUPPORTED)
 		mmc->card_caps |= MMC_CAP(SD_HS);
 
+	/* Version before 3.0 don't support UHS modes */
+	if (mmc->version < SD_VERSION_3)
+		return 0;
+
+	sd3_bus_mode = __be32_to_cpu(switch_status[3]) >> 16 & 0x1f;
+	if (sd3_bus_mode & SD_MODE_UHS_SDR104)
+		mmc->card_caps |= MMC_CAP(UHS_SDR104);
+	if (sd3_bus_mode & SD_MODE_UHS_SDR50)
+		mmc->card_caps |= MMC_CAP(UHS_SDR50);
+	if (sd3_bus_mode & SD_MODE_UHS_SDR25)
+		mmc->card_caps |= MMC_CAP(UHS_SDR25);
+	if (sd3_bus_mode & SD_MODE_UHS_SDR12)
+		mmc->card_caps |= MMC_CAP(UHS_SDR12);
+	if (sd3_bus_mode & SD_MODE_UHS_DDR50)
+		mmc->card_caps |= MMC_CAP(UHS_DDR50);
+
 	return 0;
 }
 
@@ -1059,12 +1207,35 @@ static int sd_set_card_speed(struct mmc *mmc, enum bus_mode mode)
 	int err;
 
 	ALLOC_CACHE_ALIGN_BUFFER(uint, switch_status, 16);
+	int speed;
 
-	err = sd_switch(mmc, SD_SWITCH_SWITCH, 0, 1, (u8 *)switch_status);
+	switch (mode) {
+	case SD_LEGACY:
+	case UHS_SDR12:
+		speed = UHS_SDR12_BUS_SPEED;
+		break;
+	case SD_HS:
+	case UHS_SDR25:
+		speed = UHS_SDR25_BUS_SPEED;
+		break;
+	case UHS_SDR50:
+		speed = UHS_SDR50_BUS_SPEED;
+		break;
+	case UHS_DDR50:
+		speed = UHS_DDR50_BUS_SPEED;
+		break;
+	case UHS_SDR104:
+		speed = UHS_SDR104_BUS_SPEED;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	err = sd_switch(mmc, SD_SWITCH_SWITCH, 0, speed, (u8 *)switch_status);
 	if (err)
 		return err;
 
-	if ((__be32_to_cpu(switch_status[4]) & 0x0f000000) != 0x01000000)
+	if ((__be32_to_cpu(switch_status[4]) >> 24) != speed)
 		return -ENOTSUPP;
 
 	return 0;
@@ -1199,6 +1370,11 @@ static inline int bus_width(uint cap)
 }
 
 #if !CONFIG_IS_ENABLED(DM_MMC)
+static int mmc_execute_tuning(struct mmc *mmc, uint opcode)
+{
+	return -ENOTSUPP;
+}
+
 static void mmc_send_init_stream(struct mmc *mmc)
 {
 }
@@ -1263,19 +1439,61 @@ void mmc_dump_capabilities(const char *text, uint caps)
 struct mode_width_tuning {
 	enum bus_mode mode;
 	uint widths;
+	uint tuning;
 };
 
+int mmc_voltage_to_mv(enum mmc_voltage voltage)
+{
+	switch (voltage) {
+	case MMC_SIGNAL_VOLTAGE_000: return 0;
+	case MMC_SIGNAL_VOLTAGE_330: return 3300;
+	case MMC_SIGNAL_VOLTAGE_180: return 1800;
+	case MMC_SIGNAL_VOLTAGE_120: return 1200;
+	}
+	return -EINVAL;
+}
+
 static int mmc_set_signal_voltage(struct mmc *mmc, uint signal_voltage)
 {
+	int err;
+
+	if (mmc->signal_voltage == signal_voltage)
+		return 0;
+
 	mmc->signal_voltage = signal_voltage;
-	return mmc_set_ios(mmc);
+	err = mmc_set_ios(mmc);
+	if (err)
+		debug("unable to set voltage (err %d)\n", err);
+
+	return err;
 }
 
 static const struct mode_width_tuning sd_modes_by_pref[] = {
+	{
+		.mode = UHS_SDR104,
+		.widths = MMC_MODE_4BIT | MMC_MODE_1BIT,
+		.tuning = MMC_CMD_SEND_TUNING_BLOCK
+	},
+	{
+		.mode = UHS_SDR50,
+		.widths = MMC_MODE_4BIT | MMC_MODE_1BIT,
+	},
+	{
+		.mode = UHS_DDR50,
+		.widths = MMC_MODE_4BIT | MMC_MODE_1BIT,
+	},
+	{
+		.mode = UHS_SDR25,
+		.widths = MMC_MODE_4BIT | MMC_MODE_1BIT,
+	},
 	{
 		.mode = SD_HS,
 		.widths = MMC_MODE_4BIT | MMC_MODE_1BIT,
 	},
+	{
+		.mode = UHS_SDR12,
+		.widths = MMC_MODE_4BIT | MMC_MODE_1BIT,
+	},
 	{
 		.mode = SD_LEGACY,
 		.widths = MMC_MODE_4BIT | MMC_MODE_1BIT,
@@ -1288,23 +1506,26 @@ static const struct mode_width_tuning sd_modes_by_pref[] = {
 	     mwt++) \
 		if (caps & MMC_CAP(mwt->mode))
 
-static int sd_select_mode_and_width(struct mmc *mmc)
+static int sd_select_mode_and_width(struct mmc *mmc, uint card_caps)
 {
 	int err;
 	uint widths[] = {MMC_MODE_4BIT, MMC_MODE_1BIT};
 	const struct mode_width_tuning *mwt;
+	bool uhs_en = (mmc->ocr & OCR_S18R) ? true : false;
+	uint caps;
+
 
-	err = sd_get_capabilities(mmc);
-	if (err)
-		return err;
 	/* Restrict card's capabilities by what the host can do */
-	mmc->card_caps &= (mmc->cfg->host_caps | MMC_MODE_1BIT);
+	caps = card_caps & (mmc->host_caps | MMC_MODE_1BIT);
+
+	if (!uhs_en)
+		caps &= ~UHS_CAPS;
 
-	for_each_sd_mode_by_pref(mmc->card_caps, mwt) {
+	for_each_sd_mode_by_pref(caps, mwt) {
 		uint *w;
 
 		for (w = widths; w < widths + ARRAY_SIZE(widths); w++) {
-			if (*w & mmc->card_caps & mwt->widths) {
+			if (*w & caps & mwt->widths) {
 				debug("trying mode %s width %d (at %d MHz)\n",
 				      mmc_mode_name(mwt->mode),
 				      bus_width(*w),
@@ -1325,6 +1546,16 @@ static int sd_select_mode_and_width(struct mmc *mmc)
 				mmc_select_mode(mmc, mwt->mode);
 				mmc_set_clock(mmc, mmc->tran_speed, false);
 
+				/* execute tuning if needed */
+				if (mwt->tuning && !mmc_host_is_spi(mmc)) {
+					err = mmc_execute_tuning(mmc,
+								 mwt->tuning);
+					if (err) {
+						debug("tuning failed\n");
+						goto error;
+					}
+				}
+
 				err = sd_read_ssr(mmc);
 				if (!err)
 					return 0;
@@ -1374,10 +1605,48 @@ static int mmc_read_and_compare_ext_csd(struct mmc *mmc)
 	return -EBADMSG;
 }
 
+static int mmc_set_lowest_voltage(struct mmc *mmc, enum bus_mode mode,
+				  uint32_t allowed_mask)
+{
+	u32 card_mask = 0;
+
+	switch (mode) {
+	case MMC_HS_200:
+		if (mmc->cardtype & EXT_CSD_CARD_TYPE_HS200_1_8V)
+			card_mask |= MMC_SIGNAL_VOLTAGE_180;
+		if (mmc->cardtype & EXT_CSD_CARD_TYPE_HS200_1_2V)
+			card_mask |= MMC_SIGNAL_VOLTAGE_120;
+		break;
+	case MMC_DDR_52:
+		if (mmc->cardtype & EXT_CSD_CARD_TYPE_DDR_1_8V)
+			card_mask |= MMC_SIGNAL_VOLTAGE_330 |
+				     MMC_SIGNAL_VOLTAGE_180;
+		if (mmc->cardtype & EXT_CSD_CARD_TYPE_DDR_1_2V)
+			card_mask |= MMC_SIGNAL_VOLTAGE_120;
+		break;
+	default:
+		card_mask |= MMC_SIGNAL_VOLTAGE_330;
+		break;
+	}
+
+	while (card_mask & allowed_mask) {
+		enum mmc_voltage best_match;
+
+		best_match = 1 << (ffs(card_mask & allowed_mask) - 1);
+		if (!mmc_set_signal_voltage(mmc,  best_match))
+			return 0;
+
+		allowed_mask &= ~best_match;
+	}
+
+	return -ENOTSUPP;
+}
+
 static const struct mode_width_tuning mmc_modes_by_pref[] = {
 	{
 		.mode = MMC_HS_200,
 		.widths = MMC_MODE_8BIT | MMC_MODE_4BIT,
+		.tuning = MMC_CMD_SEND_TUNING_BLOCK_HS200
 	},
 	{
 		.mode = MMC_DDR_52,
@@ -1421,18 +1690,14 @@ static const struct ext_csd_bus_width {
 	    ecbv++) \
 		if ((ddr == ecbv->is_ddr) && (caps & ecbv->cap))
 
-static int mmc_select_mode_and_width(struct mmc *mmc)
+static int mmc_select_mode_and_width(struct mmc *mmc, uint card_caps)
 {
 	int err;
 	const struct mode_width_tuning *mwt;
 	const struct ext_csd_bus_width *ecbw;
 
-	err = mmc_get_capabilities(mmc);
-	if (err)
-		return err;
-
 	/* Restrict card's capabilities by what the host can do */
-	mmc->card_caps &= (mmc->cfg->host_caps | MMC_MODE_1BIT);
+	card_caps &= (mmc->host_caps | MMC_MODE_1BIT);
 
 	/* Only version 4 of MMC supports wider bus widths */
 	if (mmc->version < MMC_VERSION_4)
@@ -1443,13 +1708,22 @@ static int mmc_select_mode_and_width(struct mmc *mmc)
 		return -ENOTSUPP;
 	}
 
-	for_each_mmc_mode_by_pref(mmc->card_caps, mwt) {
-		for_each_supported_width(mmc->card_caps & mwt->widths,
+	mmc_set_clock(mmc, mmc->legacy_speed, false);
+
+	for_each_mmc_mode_by_pref(card_caps, mwt) {
+		for_each_supported_width(card_caps & mwt->widths,
 					 mmc_is_mode_ddr(mwt->mode), ecbw) {
+			enum mmc_voltage old_voltage;
 			debug("trying mode %s width %d (at %d MHz)\n",
 			      mmc_mode_name(mwt->mode),
 			      bus_width(ecbw->cap),
 			      mmc_mode2freq(mmc, mwt->mode) / 1000000);
+			old_voltage = mmc->signal_voltage;
+			err = mmc_set_lowest_voltage(mmc, mwt->mode,
+						     MMC_ALL_SIGNAL_VOLTAGE);
+			if (err)
+				continue;
+
 			/* configure the bus width (card + host) */
 			err = mmc_switch(mmc, EXT_CSD_CMD_SET_NORMAL,
 				    EXT_CSD_BUS_WIDTH,
@@ -1479,11 +1753,21 @@ static int mmc_select_mode_and_width(struct mmc *mmc)
 			mmc_select_mode(mmc, mwt->mode);
 			mmc_set_clock(mmc, mmc->tran_speed, false);
 
+			/* execute tuning if needed */
+			if (mwt->tuning) {
+				err = mmc_execute_tuning(mmc, mwt->tuning);
+				if (err) {
+					debug("tuning failed\n");
+					goto error;
+				}
+			}
+
 			/* do a transfer to check the configuration */
 			err = mmc_read_and_compare_ext_csd(mmc);
 			if (!err)
 				return 0;
 error:
+			mmc_set_signal_voltage(mmc, old_voltage);
 			/* if an error occured, revert to a safer bus mode */
 			mmc_switch(mmc, EXT_CSD_CMD_SET_NORMAL,
 				   EXT_CSD_BUS_WIDTH, EXT_CSD_BUS_WIDTH_1);
@@ -1681,7 +1965,6 @@ static int mmc_startup(struct mmc *mmc)
 		cmd.resp_type = MMC_RSP_R1;
 		cmd.cmdarg = 1;
 		err = mmc_send_cmd(mmc, &cmd, NULL);
-
 		if (err)
 			return err;
 	}
@@ -1695,6 +1978,21 @@ static int mmc_startup(struct mmc *mmc)
 
 	err = mmc_send_cmd(mmc, &cmd, NULL);
 
+#ifdef CONFIG_MMC_QUIRKS
+	if (err && (mmc->quirks & MMC_QUIRK_RETRY_SEND_CID)) {
+		int retries = 4;
+		/*
+		 * It has been seen that SEND_CID may fail on the first
+		 * attempt, let's try a few more time
+		 */
+		do {
+			err = mmc_send_cmd(mmc, &cmd, NULL);
+			if (!err)
+				break;
+		} while (retries--);
+	}
+#endif
+
 	if (err)
 		return err;
 
@@ -1830,14 +2128,22 @@ static int mmc_startup(struct mmc *mmc)
 	if (err)
 		return err;
 
-	if (IS_SD(mmc))
-		err = sd_select_mode_and_width(mmc);
-	else
-		err = mmc_select_mode_and_width(mmc);
+	if (IS_SD(mmc)) {
+		err = sd_get_capabilities(mmc);
+		if (err)
+			return err;
+		err = sd_select_mode_and_width(mmc, mmc->card_caps);
+	} else {
+		err = mmc_get_capabilities(mmc);
+		if (err)
+			return err;
+		mmc_select_mode_and_width(mmc, mmc->card_caps);
+	}
 
 	if (err)
 		return err;
 
+	mmc->best_mode = mmc->selected_mode;
 
 	/* Fix the block length for DDR mode */
 	if (mmc->ddr_mode) {
@@ -1971,12 +2277,13 @@ static int mmc_power_on(struct mmc *mmc)
 
 static int mmc_power_off(struct mmc *mmc)
 {
+	mmc_set_clock(mmc, 1, true);
 #if CONFIG_IS_ENABLED(DM_MMC) && CONFIG_IS_ENABLED(DM_REGULATOR)
 	if (mmc->vmmc_supply) {
 		int ret = regulator_set_enable(mmc->vmmc_supply, false);
 
 		if (ret) {
-			puts("Error disabling VMMC supply\n");
+			debug("Error disabling VMMC supply\n");
 			return ret;
 		}
 	}
@@ -2002,8 +2309,11 @@ static int mmc_power_cycle(struct mmc *mmc)
 int mmc_start_init(struct mmc *mmc)
 {
 	bool no_card;
+	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)
@@ -2027,7 +2337,23 @@ int mmc_start_init(struct mmc *mmc)
 	if (err)
 		return err;
 
-	err = mmc_power_on(mmc);
+#ifdef CONFIG_MMC_QUIRKS
+	mmc->quirks = MMC_QUIRK_RETRY_SET_BLOCKLEN |
+		      MMC_QUIRK_RETRY_SEND_CID;
+#endif
+
+	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;
 
@@ -2041,6 +2367,7 @@ int mmc_start_init(struct mmc *mmc)
 #endif
 	mmc->ddr_mode = 0;
 
+retry:
 	mmc_set_initial_state(mmc);
 	mmc_send_init_stream(mmc);
 
@@ -2057,7 +2384,12 @@ int mmc_start_init(struct mmc *mmc)
 	err = mmc_send_if_cond(mmc);
 
 	/* Now try to get the SD card's operating condition */
-	err = sd_send_op_cond(mmc);
+	err = sd_send_op_cond(mmc, uhs_en);
+	if (err && uhs_en) {
+		uhs_en = false;
+		mmc_power_cycle(mmc);
+		goto retry;
+	}
 
 	/* If the command timed out, we check for an MMC card */
 	if (err == -ETIMEDOUT) {