mmc: sdhci-of-esdhc: poll ESDHC_FLUSH_ASYNC_FIFO bit until completion

The ESDHC_FLUSH_ASYNC_FIFO bit which is set to flush asynchronous FIFO
should be polled until it's auto cleared by hardware.
Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci-of-esdhc.c

@@ -560,6 +560,32 @@ static void esdhc_clock_enable(struct sdhci_host *host, bool enable)
 	}
 }
 
+static void esdhc_flush_async_fifo(struct sdhci_host *host)
+{
+	ktime_t timeout;
+	u32 val;
+
+	val = sdhci_readl(host, ESDHC_DMA_SYSCTL);
+	val |= ESDHC_FLUSH_ASYNC_FIFO;
+	sdhci_writel(host, val, ESDHC_DMA_SYSCTL);
+
+	/* Wait max 20 ms */
+	timeout = ktime_add_ms(ktime_get(), 20);
+	while (1) {
+		bool timedout = ktime_after(ktime_get(), timeout);
+
+		if (!(sdhci_readl(host, ESDHC_DMA_SYSCTL) &
+		      ESDHC_FLUSH_ASYNC_FIFO))
+			break;
+		if (timedout) {
+			pr_err("%s: flushing asynchronous FIFO timeout.\n",
+				mmc_hostname(host->mmc));
+			break;
+		}
+		usleep_range(10, 20);
+	}
+}
+
 static void esdhc_of_set_clock(struct sdhci_host *host, unsigned int clock)
 {
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
@@ -652,9 +678,7 @@ static void esdhc_of_set_clock(struct sdhci_host *host, unsigned int clock)
 		sdhci_writel(host, temp | ESDHC_HS400_WNDW_ADJUST, ESDHC_TBCTL);
 
 		esdhc_clock_enable(host, false);
-		temp = sdhci_readl(host, ESDHC_DMA_SYSCTL);
-		temp |= ESDHC_FLUSH_ASYNC_FIFO;
-		sdhci_writel(host, temp, ESDHC_DMA_SYSCTL);
+		esdhc_flush_async_fifo(host);
 	}
 
 	/* Wait max 20 ms */
@@ -814,10 +838,7 @@ static void esdhc_tuning_block_enable(struct sdhci_host *host, bool enable)
 	u32 val;
 
 	esdhc_clock_enable(host, false);
-
-	val = sdhci_readl(host, ESDHC_DMA_SYSCTL);
-	val |= ESDHC_FLUSH_ASYNC_FIFO;
-	sdhci_writel(host, val, ESDHC_DMA_SYSCTL);
+	esdhc_flush_async_fifo(host);
 
 	val = sdhci_readl(host, ESDHC_TBCTL);
 	if (enable)