[U-Boot] [PATCH 37/41] mmc: fsl_esdhc: fix sd/mmc ddr mode clock setting issue

[Peng Fan]

From: Ye Li <ye.li at nxp.com>

When sd/mmc work at DDR mode, like HS400/HS400ES/DDR52/DDR50 mode,
the actual clock rate is just half of the expected clock.

This patch set the DDR_EN bit first for DDR mode, hardware divide
the usdhc clock automatically, then follow the original sdr clock
setting method.

Signed-off-by: Haibo Chen <haibo.chen at nxp.com>
Signed-off-by: Ye Li <ye.li at nxp.com>
---
 drivers/mmc/fsl_esdhc.c | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/drivers/mmc/fsl_esdhc.c b/drivers/mmc/fsl_esdhc.c
index 1b062ff06d..bf4ae74847 100644
--- a/drivers/mmc/fsl_esdhc.c
+++ b/drivers/mmc/fsl_esdhc.c
@@ -583,18 +583,32 @@ static void set_sysctl(struct fsl_esdhc_priv *priv, struct mmc *mmc, uint clock)
 #else
 	int pre_div = 2;
 #endif
-	int ddr_pre_div = mmc->ddr_mode ? 2 : 1;
 	int sdhc_clk = priv->sdhc_clk;
 	uint clk;
 
+	/*
+	 * For ddr mode, usdhc need to enable DDR mode first, after select
+	 * this DDR mode, usdhc will automatically divide the usdhc clock
+	 */
+	if (mmc->ddr_mode) {
+		writel(readl(&regs->mixctrl) | MIX_CTRL_DDREN, &regs->mixctrl);
+		sdhc_clk >>= 1;
+	}
+
 	if (clock < mmc->cfg->f_min)
 		clock = mmc->cfg->f_min;
 
-	while (sdhc_clk / (16 * pre_div * ddr_pre_div) > clock && pre_div < 256)
-		pre_div *= 2;
+	if ((sdhc_clk / 16) > clock) {
+		for (; pre_div < 256; pre_div *= 2)
+			if ((sdhc_clk / pre_div) <= (clock * 16))
+				break;
+	} else {
+		pre_div = 1;
+	}
 
-	while (sdhc_clk / (div * pre_div * ddr_pre_div) > clock && div < 16)
-		div++;
+	for (div = 1; div <= 16; div++)
+		if ((sdhc_clk / (div * pre_div)) <= clock)
+			break;
 
 	pre_div >>= 1;
 	div -= 1;
-- 
2.14.1