ARM: OMAP4: MMC: increase delay for pbias

4 micro seconds is not enough for PBIAS if MMC regulator is
enabled from MMC regulator OFF.
Increase the delay for PBIAS to stabilize.
Wait for PBIAS and timeout if not.

Resolves MMC/SD failure on OMAP4
"Pbias Voltage is not same as LDO"

Signed-off-by: Balaji T K <balajitk@ti.com>
Acked-by:  Kishore Kadiyala <kishore.kadiyala@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

diff --git a/arch/arm/mach-omap2/hsmmc.c b/arch/arm/mach-omap2/hsmmc.c
index 857f7daa3286b234956bd1767e3738cc6d44a964..66868c5d5a29b8207da355ef7163e941296f615c 100644 (file)
--- a/arch/arm/mach-omap2/hsmmc.c
+++ b/arch/arm/mach-omap2/hsmmc.c
@@ -145,6 +145,7 @@ static void omap4_hsmmc1_after_set_reg(struct device *dev, int slot,
                                 int power_on, int vdd)
 {
        u32 reg;
+       unsigned long timeout;
 
        if (power_on) {
                reg = omap4_ctrl_pad_readl(control_pbias_offset);
@@ -157,9 +158,15 @@ static void omap4_hsmmc1_after_set_reg(struct device *dev, int slot,
                        OMAP4_MMC1_PWRDNZ_MASK |
                        OMAP4_USBC1_ICUSB_PWRDNZ_MASK);
                omap4_ctrl_pad_writel(reg, control_pbias_offset);
-               /* 4 microsec delay for comparator to generate an error*/
-               udelay(4);
-               reg = omap4_ctrl_pad_readl(control_pbias_offset);
+
+               timeout = jiffies + msecs_to_jiffies(5);
+               do {
+                       reg = omap4_ctrl_pad_readl(control_pbias_offset);
+                       if (!(reg & OMAP4_MMC1_PBIASLITE_VMODE_ERROR_MASK))
+                               break;
+                       usleep_range(100, 200);
+               } while (!time_after(jiffies, timeout));
+
                if (reg & OMAP4_MMC1_PBIASLITE_VMODE_ERROR_MASK) {
                        pr_err("Pbias Voltage is not same as LDO\n");
                        /* Caution : On VMODE_ERROR Power Down MMC IO */