[PATCH] mmc: omap_hsmmc: Fix sleep too long in ISR context.

From: majianpeng
Date: Wed Jul 31 2013 - 22:30:37 EST


We found a problem when we removed a working sd card that the irqaction
of omap_hsmmc can sleep to 3.6s. This cause our watchdog to work.
In func omap_hsmmc_reset_controller_fsm, it should watch a 0->1
transition.It used loops_per_jiffy as the timer.
The code is:
> while ((!(OMAP_HSMMC_READ(host->base, SYSCTL) & bit))
> && (i++ < limit))
> cpu_relax();
But the loops_per_jiffy is:
> while(i++ < limit)
> cpu_relax();
It add some codes so the time became long.
Becasue those codes in ISR context, it can't use timer_before/after.
I divived the time into 1ms and used udelay(1) to instead.
It will cause do additional udelay(1).But from my test,it looks good.

Reported-by: Yuzheng Ma <mayuzheng@xxxxxxxxxxx>
Tested-by: Yuzheng Ma <mayuzheng@xxxxxxxxxxx>
Signed-off-by: Jianpeng Ma <majianpeng@xxxxxxxxx>
---
drivers/mmc/host/omap_hsmmc.c | 20 +++++++++++++-------
1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c
index 1865321..96daca1 100644
--- a/drivers/mmc/host/omap_hsmmc.c
+++ b/drivers/mmc/host/omap_hsmmc.c
@@ -977,6 +977,8 @@ static inline void omap_hsmmc_reset_controller_fsm(struct omap_hsmmc_host *host,
unsigned long limit = (loops_per_jiffy *
msecs_to_jiffies(MMC_TIMEOUT_MS));

+ /*Divided time into us for unit 1,we can use udelay(1)*/
+ i = limit / (MMC_TIMEOUT_MS * 1000);
OMAP_HSMMC_WRITE(host->base, SYSCTL,
OMAP_HSMMC_READ(host->base, SYSCTL) | bit);

@@ -985,15 +987,19 @@ static inline void omap_hsmmc_reset_controller_fsm(struct omap_hsmmc_host *host,
* Monitor a 0->1 transition first
*/
if (mmc_slot(host).features & HSMMC_HAS_UPDATED_RESET) {
- while ((!(OMAP_HSMMC_READ(host->base, SYSCTL) & bit))
- && (i++ < limit))
- cpu_relax();
+ while (i--) {
+ if ((OMAP_HSMMC_READ(host->base, SYSCTL) & bit))
+ break;
+ udelay(1);
+ }
}
- i = 0;

- while ((OMAP_HSMMC_READ(host->base, SYSCTL) & bit) &&
- (i++ < limit))
- cpu_relax();
+ i = limit / (MMC_TIMEOUT_MS * 1000);
+ while (i--) {
+ if (!(OMAP_HSMMC_READ(host->base, SYSCTL) & bit))
+ break;
+ udealy(1);
+ }

if (OMAP_HSMMC_READ(host->base, SYSCTL) & bit)
dev_err(mmc_dev(host->mmc),
--
1.8.1.2


Thanks!
Jianpeng MaN?叉??y??b??千v??藓{.n???{?赙zXФ?塄}?财??j:+v???赙zZ+?zf"?????i????ア??璀??撷f?^j谦y??@A?囤?0鹅h??i