[PATCH v1] i.MX: esdhc: optimize set_ios path

[Oleksij Rempel]

this part of code is executed at least 4 times in eMMC probe sequence.
Optimizing it is reducing 20-30 msec of boot time.

Signed-off-by: Oleksij Rempel <o.rempel at pengutronix.de>
---
 drivers/mci/imx-esdhc.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/mci/imx-esdhc.c b/drivers/mci/imx-esdhc.c
index 141d715c90..5c2a3a36e3 100644
--- a/drivers/mci/imx-esdhc.c
+++ b/drivers/mci/imx-esdhc.c
@@ -95,6 +95,7 @@ struct fsl_esdhc_host {
 	struct device_d		*dev;
 	struct clk		*clk;
 	const struct esdhc_soc_data *socdata;
+	u32			last_clock;
 };
 
 #define to_fsl_esdhc(mci)	container_of(mci, struct fsl_esdhc_host, mci)
@@ -408,7 +409,7 @@ esdhc_send_cmd(struct mci_host *mci, struct mci_cmd *cmd, struct mci_data *data)
 
 static void set_sysctl(struct mci_host *mci, u32 clock)
 {
-	int div, pre_div;
+	int div, pre_div, i;
 	struct fsl_esdhc_host *host = to_fsl_esdhc(mci);
 	void __iomem *regs = host->regs;
 	int sdhc_clk = clk_get_rate(host->clk);
@@ -453,13 +454,17 @@ static void set_sysctl(struct mci_host *mci, u32 clock)
 	esdhc_clrsetbits32(regs + SDHCI_CLOCK_CONTROL__TIMEOUT_CONTROL__SOFTWARE_RESET,
 			SYSCTL_CLOCK_MASK, clk);
 
-	wait_on_timeout(10 * MSECOND,
-			!(esdhc_read32(regs + SDHCI_PRESENT_STATE) & PRSSTAT_SDSTB));
+	for (i = 0; i < 1000; i++) {
+		if (esdhc_read32(regs + SDHCI_PRESENT_STATE) & PRSSTAT_SDSTB)
+			break;
+		udelay(10);
+	}
 
 	clk = SYSCTL_PEREN | SYSCTL_CKEN;
 
 	esdhc_setbits32(regs + SDHCI_CLOCK_CONTROL__TIMEOUT_CONTROL__SOFTWARE_RESET,
 			clk);
+	host->last_clock = clock;
 }
 
 static void esdhc_set_ios(struct mci_host *mci, struct mci_ios *ios)
@@ -468,7 +473,8 @@ static void esdhc_set_ios(struct mci_host *mci, struct mci_ios *ios)
 	void __iomem *regs = host->regs;
 
 	/* Set the clock speed */
-	set_sysctl(mci, ios->clock);
+	if (host->last_clock != ios->clock)
+		set_sysctl(mci, ios->clock);
 
 	/* Set the bus width */
 	esdhc_clrbits32(regs + SDHCI_HOST_CONTROL__POWER_CONTROL__BLOCK_GAP_CONTROL,
-- 
2.11.0