mmc: sdhci: Disable re-tuning for HS400

index 73de62a..b3d68e0 100644
@@ -259,8 +259,6 @@ static void sdhci_reinit(struct sdhci_host *host)
 
 		del_timer_sync(&host->tuning_timer);
 		host->flags &= ~SDHCI_NEEDS_RETUNING;
-		host->mmc->max_blk_count =
-			(host->quirks & SDHCI_QUIRK_NO_MULTIBLOCK) ? 1 : 65535;
 	}
 	sdhci_enable_card_detection(host);
 }

@@ -2048,8 +2046,6 @@ out:
 		host->flags |= SDHCI_USING_RETUNING_TIMER;
 		mod_timer(&host->tuning_timer, jiffies +
 			host->tuning_count * HZ);
-		/* Tuning mode 1 limits the maximum data length to 4MB */
-		mmc->max_blk_count = (4 * 1024 * 1024) / mmc->max_blk_size;
 	} else if (host->flags & SDHCI_USING_RETUNING_TIMER) {
 		host->flags &= ~SDHCI_NEEDS_RETUNING;
 		/* Reload the new initial value for timer */

@@ -3263,8 +3259,9 @@ int sdhci_add_host(struct sdhci_host *host)
 		mmc->max_segs = SDHCI_MAX_SEGS;
 
 	/*
-	 * Maximum number of sectors in one transfer. Limited by DMA boundary
-	 * size (512KiB).
+	 * Maximum number of sectors in one transfer. Limited by SDMA boundary
+	 * size (512KiB). Note some tuning modes impose a 4MiB limit, but this
+	 * is less anyway.
 	 */
 	mmc->max_req_size = 524288;
 

index b3d68e0..2efa7fe 100644
@@ -1909,9 +1909,7 @@ static int sdhci_execute_tuning(struct mmc_host *mmc, u32 opcode)
 		/* FALLTHROUGH */
 
 	default:
-		spin_unlock_irqrestore(&host->lock, flags);
-		sdhci_runtime_pm_put(host);
-		return 0;
+		goto out_unlock;
 	}
 
 	if (host->ops->platform_execute_tuning) {

@@ -2066,6 +2064,7 @@ out:
 
 	sdhci_writel(host, host->ier, SDHCI_INT_ENABLE);
 	sdhci_writel(host, host->ier, SDHCI_SIGNAL_ENABLE);
+out_unlock:
 	spin_unlock_irqrestore(&host->lock, flags);
 	sdhci_runtime_pm_put(host);
 

index 2efa7fe..ff0fe90 100644
@@ -1885,10 +1885,14 @@ static int sdhci_execute_tuning(struct mmc_host *mmc, u32 opcode)
 	int tuning_loop_counter = MAX_TUNING_LOOP;
 	int err = 0;
 	unsigned long flags;
+	unsigned int tuning_count = 0;
 
 	sdhci_runtime_pm_get(host);
 	spin_lock_irqsave(&host->lock, flags);
 
+	if (host->tuning_mode == SDHCI_TUNING_MODE_1)
+		tuning_count = host->tuning_count;
+
 	/*
 	 * The Host Controller needs tuning only in case of SDR104 mode
 	 * and for SDR50 mode when Use Tuning for SDR50 is set in the

@@ -2033,22 +2037,11 @@ static int sdhci_execute_tuning(struct mmc_host *mmc, u32 opcode)
 	}
 
 out:
-	/*
-	 * If this is the very first time we are here, we start the retuning
-	 * timer. Since only during the first time, SDHCI_NEEDS_RETUNING
-	 * flag won't be set, we check this condition before actually starting
-	 * the timer.
-	 */
-	if (!(host->flags & SDHCI_NEEDS_RETUNING) && host->tuning_count &&
-	    (host->tuning_mode == SDHCI_TUNING_MODE_1)) {
+	host->flags &= ~SDHCI_NEEDS_RETUNING;
+
+	if (tuning_count) {
 		host->flags |= SDHCI_USING_RETUNING_TIMER;
-		mod_timer(&host->tuning_timer, jiffies +
-			host->tuning_count * HZ);
-	} else if (host->flags & SDHCI_USING_RETUNING_TIMER) {
-		host->flags &= ~SDHCI_NEEDS_RETUNING;
-		/* Reload the new initial value for timer */
-		mod_timer(&host->tuning_timer, jiffies +
-			  host->tuning_count * HZ);
+		mod_timer(&host->tuning_timer, jiffies + tuning_count * HZ);
 	}
 
 	/*

index ff0fe90..bfde165 100644
@@ -1878,6 +1878,18 @@ static int sdhci_card_busy(struct mmc_host *mmc)
 	return !(present_state & SDHCI_DATA_LVL_MASK);
 }
 
+static int sdhci_prepare_hs400_tuning(struct mmc_host *mmc, struct mmc_ios *ios)
+{
+	struct sdhci_host *host = mmc_priv(mmc);
+	unsigned long flags;
+
+	spin_lock_irqsave(&host->lock, flags);
+	host->flags |= SDHCI_HS400_TUNING;
+	spin_unlock_irqrestore(&host->lock, flags);
+
+	return 0;
+}
+
 static int sdhci_execute_tuning(struct mmc_host *mmc, u32 opcode)
 {
 	struct sdhci_host *host = mmc_priv(mmc);

@@ -1886,10 +1898,14 @@ static int sdhci_execute_tuning(struct mmc_host *mmc, u32 opcode)
 	int err = 0;
 	unsigned long flags;
 	unsigned int tuning_count = 0;
+	bool hs400_tuning;
 
 	sdhci_runtime_pm_get(host);
 	spin_lock_irqsave(&host->lock, flags);
 
+	hs400_tuning = host->flags & SDHCI_HS400_TUNING;
+	host->flags &= ~SDHCI_HS400_TUNING;
+
 	if (host->tuning_mode == SDHCI_TUNING_MODE_1)
 		tuning_count = host->tuning_count;
 

@@ -1901,8 +1917,20 @@ static int sdhci_execute_tuning(struct mmc_host *mmc, u32 opcode)
 	 * tuning function has to be executed.
 	 */
 	switch (host->timing) {
+	/* HS400 tuning is done in HS200 mode */
 	case MMC_TIMING_MMC_HS400:
+		err = -EINVAL;
+		goto out_unlock;
+
 	case MMC_TIMING_MMC_HS200:
+		/*
+		 * Periodic re-tuning for HS400 is not expected to be needed, so
+		 * disable it here.
+		 */
+		if (hs400_tuning)
+			tuning_count = 0;
+		break;
+
 	case MMC_TIMING_UHS_SDR104:
 		break;
 

@@ -2130,6 +2158,7 @@ static const struct mmc_host_ops sdhci_ops = {
 	.hw_reset	= sdhci_hw_reset,
 	.enable_sdio_irq = sdhci_enable_sdio_irq,
 	.start_signal_voltage_switch	= sdhci_start_signal_voltage_switch,
+	.prepare_hs400_tuning		= sdhci_prepare_hs400_tuning,
 	.execute_tuning			= sdhci_execute_tuning,
 	.card_event			= sdhci_card_event,
 	.card_busy	= sdhci_card_busy,

index 375af80..f767a0d 100644
@@ -137,6 +137,7 @@ struct sdhci_host {
 #define SDHCI_SDR104_NEEDS_TUNING (1<<10)	/* SDR104/HS200 needs tuning */
 #define SDHCI_USING_RETUNING_TIMER (1<<11)	/* Host is using a retuning timer for the card */
 #define SDHCI_USE_64_BIT_DMA	(1<<12)	/* Use 64-bit DMA */
+#define SDHCI_HS400_TUNING	(1<<13)	/* Tuning for HS400 */
 
 	unsigned int version;	/* SDHCI spec. version */