回复: About omap2 mmc host close too long irq in irqaction.

[Balaji T K]

On Thursday 18 July 2013 02:13 PM, majianpeng wrote:
>> Hi all,
>> 	Now i worked on omp2 and met a probelm which someplace close_irq for 3.6second.
>> The kernel version is 2.6.37. I used trace to find in irq_action:omap_hsmmc_irq.
>> This problem occured by removed the sdcard when there are io operations.
>>
>> I found the read problem is in omap_hsmmc_reset_controller_fsm.
>> In omap_hsmmc_reset_controller_fsm:
>>> static inline void omap_hsmmc_reset_controller_fsm(struct omap_hsmmc_host *host,
>>>                                                    unsigned long bit)
>>> {
>>>         unsigned long i = 0;
>>>         unsigned long limit = (loops_per_jiffy *
>>>                                 msecs_to_jiffies(MMC_TIMEOUT_MS));
>>
>>>         OMAP_HSMMC_WRITE(host->base, SYSCTL,
>>>                          OMAP_HSMMC_READ(host->base, SYSCTL) | bit);
>>
>>>         /*
>>>          * OMAP4 ES2 and greater has an updated reset logic.
>>>          * 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();
>>         }
>> In func, it used loops_per_jiffy  in order to avoid do many time exceed MMC_TIMEOUT_MS.
>> In face oops_per_jiify is like:
>> while(i++ < loops_per_jiffy)
>> 	cpu_relax();
>> But actually, it used as follow:
>>> while ((!(OMAP_HSMMC_READ(host->base, SYSCTL) & bit))
>>>                                       && (i++ < limit))
>> it add some operations like: read regisger, &, &&.
>> So the time may exceed MMC_TIMEOUT_MS.
>> I used those code to test and found it's ok:
>> for (i = 0 ; i < 10; i++){
>> 	if (!(OMAP_HSMMC_READ(host->base, SYSCTL) & bit))
>> 		  break;
>> 	j = limit/10;
>> 	while(j--)
>> 		cpu_relax();
>> }
>>
>> Using this the problom can't occur.
>> Am i missing something?
>>
>> Thanks!
>> Jianpeng Ma
> I do more test and found more interesting things
> 
> static inline void omap_hsmmc_reset_controller_fsm(struct omap_hsmmc_host *host,
>                                                     unsigned long bit)
> {
>        
> 
>          /*
>           * OMAP4 ES2 and greater has an updated reset logic.
>           * 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();
> 	I modify above code as:
> 				while ((!(OMAP_HSMMC_READ(host->base, SYSCTL) & bit)) {
> 							i++;cpu_relax();
> 				}
>   When the problem occur, it  can't return from while.That's mean  the transition was already oocured befroe while.
> So it can't monitor a 0->1 transition.

Hi,

Which OMAP SoC are you testing on (OMAP4 ES2+ ? )

Can you try the below inlined patch

diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c
index eccedc7..7dbc83f 100644
--- a/drivers/mmc/host/omap_hsmmc.c
+++ b/drivers/mmc/host/omap_hsmmc.c
@@ -973,10 +973,9 @@ static inline void omap_hsmmc_dbg_report_irq(struct omap_hsmmc_host *host,
 static inline void omap_hsmmc_reset_controller_fsm(struct omap_hsmmc_host *host,
 						   unsigned long bit)
 {
-	unsigned long i = 0;
-	unsigned long limit = (loops_per_jiffy *
-				msecs_to_jiffies(MMC_TIMEOUT_MS));
+	unsigned long timeout;

+	timeout = jiffies + msecs_to_jiffies(MMC_TIMEOUT_MS);
 	OMAP_HSMMC_WRITE(host->base, SYSCTL,
 			 OMAP_HSMMC_READ(host->base, SYSCTL) | bit);

@@ -985,14 +984,14 @@ 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))
+		while ((!(OMAP_HSMMC_READ(host->base, SYSCTL) & bit)) &&
+			time_before(jiffies, timeout))
 			cpu_relax();
 	}
-	i = 0;

+	timeout = jiffies + msecs_to_jiffies(MMC_TIMEOUT_MS);
 	while ((OMAP_HSMMC_READ(host->base, SYSCTL) & bit) &&
-		(i++ < limit))
+		time_before(jiffies, timeout))
 		cpu_relax();

 	if (OMAP_HSMMC_READ(host->base, SYSCTL) & bit)
-- 
> 
> Thanks!
> Jianpeng Ma
>