mmc: sd: UHS-I bus speed should be set last in UHS initialization

mmc_sd_init_uhs_card function sets the driver type, current limit
and bus speed mode on card as well as on host controller side.

Currently bus speed mode is set by sending CMD6 to card and
immediately setting the timing mode in host controller. But
then before initiating tuning sequence, it also tries to set
current limit by sending CMD6 to card which results in data
timeout errors in controller if bus speed mode is SDR50/SDR104 mode.

So basically bus speed mode should be set only after current limit
is set in the card and immediately after setting the bus speed mode,
tuning sequence should be initiated.
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
Reviewed-by: Arindam Nath <arindam.nath@amd.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/core/sd.c

@@ -469,56 +469,75 @@ static int sd_select_driver_type(struct mmc_card *card, u8 *status)
 	return 0;
 }
 
-static int sd_set_bus_speed_mode(struct mmc_card *card, u8 *status)
+static void sd_update_bus_speed_mode(struct mmc_card *card)
 {
-	unsigned int bus_speed = 0, timing = 0;
-	int err;
-
 	/*
 	 * If the host doesn't support any of the UHS-I modes, fallback on
 	 * default speed.
 	 */
 	if (!(card->host->caps & (MMC_CAP_UHS_SDR12 | MMC_CAP_UHS_SDR25 |
-	    MMC_CAP_UHS_SDR50 | MMC_CAP_UHS_SDR104 | MMC_CAP_UHS_DDR50)))
-		return 0;
+	    MMC_CAP_UHS_SDR50 | MMC_CAP_UHS_SDR104 | MMC_CAP_UHS_DDR50))) {
+		card->sd_bus_speed = 0;
+		return;
+	}
 
 	if ((card->host->caps & MMC_CAP_UHS_SDR104) &&
 	    (card->sw_caps.sd3_bus_mode & SD_MODE_UHS_SDR104)) {
-			bus_speed = UHS_SDR104_BUS_SPEED;
-			timing = MMC_TIMING_UHS_SDR104;
-			card->sw_caps.uhs_max_dtr = UHS_SDR104_MAX_DTR;
+			card->sd_bus_speed = UHS_SDR104_BUS_SPEED;
 	} else if ((card->host->caps & MMC_CAP_UHS_DDR50) &&
 		   (card->sw_caps.sd3_bus_mode & SD_MODE_UHS_DDR50)) {
-			bus_speed = UHS_DDR50_BUS_SPEED;
-			timing = MMC_TIMING_UHS_DDR50;
-			card->sw_caps.uhs_max_dtr = UHS_DDR50_MAX_DTR;
+			card->sd_bus_speed = UHS_DDR50_BUS_SPEED;
 	} else if ((card->host->caps & (MMC_CAP_UHS_SDR104 |
 		    MMC_CAP_UHS_SDR50)) && (card->sw_caps.sd3_bus_mode &
 		    SD_MODE_UHS_SDR50)) {
-			bus_speed = UHS_SDR50_BUS_SPEED;
-			timing = MMC_TIMING_UHS_SDR50;
-			card->sw_caps.uhs_max_dtr = UHS_SDR50_MAX_DTR;
+			card->sd_bus_speed = UHS_SDR50_BUS_SPEED;
 	} else if ((card->host->caps & (MMC_CAP_UHS_SDR104 |
 		    MMC_CAP_UHS_SDR50 | MMC_CAP_UHS_SDR25)) &&
 		   (card->sw_caps.sd3_bus_mode & SD_MODE_UHS_SDR25)) {
-			bus_speed = UHS_SDR25_BUS_SPEED;
-			timing = MMC_TIMING_UHS_SDR25;
-			card->sw_caps.uhs_max_dtr = UHS_SDR25_MAX_DTR;
+			card->sd_bus_speed = UHS_SDR25_BUS_SPEED;
 	} else if ((card->host->caps & (MMC_CAP_UHS_SDR104 |
 		    MMC_CAP_UHS_SDR50 | MMC_CAP_UHS_SDR25 |
 		    MMC_CAP_UHS_SDR12)) && (card->sw_caps.sd3_bus_mode &
 		    SD_MODE_UHS_SDR12)) {
-			bus_speed = UHS_SDR12_BUS_SPEED;
-			timing = MMC_TIMING_UHS_SDR12;
-			card->sw_caps.uhs_max_dtr = UHS_SDR12_MAX_DTR;
+			card->sd_bus_speed = UHS_SDR12_BUS_SPEED;
+	}
+}
+
+static int sd_set_bus_speed_mode(struct mmc_card *card, u8 *status)
+{
+	int err;
+	unsigned int timing = 0;
+
+	switch (card->sd_bus_speed) {
+	case UHS_SDR104_BUS_SPEED:
+		timing = MMC_TIMING_UHS_SDR104;
+		card->sw_caps.uhs_max_dtr = UHS_SDR104_MAX_DTR;
+		break;
+	case UHS_DDR50_BUS_SPEED:
+		timing = MMC_TIMING_UHS_DDR50;
+		card->sw_caps.uhs_max_dtr = UHS_DDR50_MAX_DTR;
+		break;
+	case UHS_SDR50_BUS_SPEED:
+		timing = MMC_TIMING_UHS_SDR50;
+		card->sw_caps.uhs_max_dtr = UHS_SDR50_MAX_DTR;
+		break;
+	case UHS_SDR25_BUS_SPEED:
+		timing = MMC_TIMING_UHS_SDR25;
+		card->sw_caps.uhs_max_dtr = UHS_SDR25_MAX_DTR;
+		break;
+	case UHS_SDR12_BUS_SPEED:
+		timing = MMC_TIMING_UHS_SDR12;
+		card->sw_caps.uhs_max_dtr = UHS_SDR12_MAX_DTR;
+		break;
+	default:
+		return 0;
 	}
 
-	card->sd_bus_speed = bus_speed;
-	err = mmc_sd_switch(card, 1, 0, bus_speed, status);
+	err = mmc_sd_switch(card, 1, 0, card->sd_bus_speed, status);
 	if (err)
 		return err;
 
-	if ((status[16] & 0xF) != bus_speed)
+	if ((status[16] & 0xF) != card->sd_bus_speed)
 		printk(KERN_WARNING "%s: Problem setting bus speed mode!\n",
 			mmc_hostname(card->host));
 	else {
@@ -618,18 +637,24 @@ static int mmc_sd_init_uhs_card(struct mmc_card *card)
 		mmc_set_bus_width(card->host, MMC_BUS_WIDTH_4);
 	}
 
+	/*
+	 * Select the bus speed mode depending on host
+	 * and card capability.
+	 */
+	sd_update_bus_speed_mode(card);
+
 	/* Set the driver strength for the card */
 	err = sd_select_driver_type(card, status);
 	if (err)
 		goto out;
 
-	/* Set bus speed mode of the card */
-	err = sd_set_bus_speed_mode(card, status);
+	/* Set current limit for the card */
+	err = sd_set_current_limit(card, status);
 	if (err)
 		goto out;
 
-	/* Set current limit for the card */
-	err = sd_set_current_limit(card, status);
+	/* Set bus speed mode of the card */
+	err = sd_set_bus_speed_mode(card, status);
 	if (err)
 		goto out;