MMC: DWMMC: Fix FIFO_DEPTH calculation

Current DWMMC driver used to give FIFO underrun/overrun error every 3rd time
for mmc rescan command.
In current code FIFO_DEPTH is getting calculated after reading the default FIFOTH
register and extracting the RX_WMARK bits from it i.e (RX_WMARK = FIFO_DEPTH/2 -1).
Instead of storing the correct value, we were recalculating the FIFO_DEPT each
time which is not correct.

Based on "[PATCH V9 3/9] DWMMC: Initialise dwmci and resolve EMMC read write issues"
http://permalink.gmane.org/gmane.comp.boot-loaders.u-boot/160247

Signed-off-by: Hatim Ali <hatim.rv@samsung.com>
Signed-off-by: Rajeshwari Shinde <rajeshwari.s@samsung.com>
Acked-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
Acked-by: Jaehoon Chung <jh80.chung@samsung.com>
Acked-by: Andy Fleming <afleming@freescale.com>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>

drivers/mmc/dw_mmc.c

@@ -312,7 +312,7 @@ static void dwmci_set_ios(struct mmc *mmc)
 static int dwmci_init(struct mmc *mmc)
 {
 	struct dwmci_host *host = (struct dwmci_host *)mmc->priv;
-	u32 fifo_size, fifoth_val;
+	u32 fifo_size;
 
 	dwmci_writel(host, DWMCI_PWREN, 1);
 
@@ -332,15 +332,13 @@ static int dwmci_init(struct mmc *mmc)
 	dwmci_writel(host, DWMCI_IDINTEN, 0);
 	dwmci_writel(host, DWMCI_BMOD, 1);
 
-	fifo_size = dwmci_readl(host, DWMCI_FIFOTH);
-	fifo_size = ((fifo_size & RX_WMARK_MASK) >> RX_WMARK_SHIFT) + 1;
-	if (host->fifoth_val) {
-		fifoth_val = host->fifoth_val;
-	} else {
-		fifoth_val = MSIZE(0x2) | RX_WMARK(fifo_size / 2 - 1) |
+	if (!host->fifoth_val) {
+		fifo_size = dwmci_readl(host, DWMCI_FIFOTH);
+		fifo_size = ((fifo_size & RX_WMARK_MASK) >> RX_WMARK_SHIFT) + 1;
+		host->fifoth_val = MSIZE(0x2) | RX_WMARK(fifo_size / 2 - 1) |
 			TX_WMARK(fifo_size / 2);
 	}
-	dwmci_writel(host, DWMCI_FIFOTH, fifoth_val);
+	dwmci_writel(host, DWMCI_FIFOTH, host->fifoth_val);
 
 	dwmci_writel(host, DWMCI_CLKENA, 0);
 	dwmci_writel(host, DWMCI_CLKSRC, 0);