[PATCH 1/2] ARM: OMAP4: MMC: increase delay for pbias

[T Krishnamoorthy, Balaji]

On Wed, Jun 1, 2011 at 1:11 PM, Tony Lindgren <tony at atomide.com> wrote:
> * Balaji T K <balajitk at ti.com> [110530 07:23]:
>> 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 at ti.com>
>> ---
>>  arch/arm/mach-omap2/hsmmc.c |   13 ++++++++++---
>>  1 files changed, 10 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/arm/mach-omap2/hsmmc.c b/arch/arm/mach-omap2/hsmmc.c
>> index b2f30be..3f8dc16 100644
>> --- 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;
>> +                     udelay(100);
>> +             } 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 */
>
> Actually, can you check if you can use usleep_range here as recommended
> by checkpatch.pl?

sure, fixing it in v2

>
> Tony
>