Hi,

Thanks you for the test.

here a new version of the patch. It doesn't replace mdelay with jiffies 
anymore. It changes mdelay to udelay (the granularity of 1 ms becomes 10 
us).
I didn't mesure irq off latency with this patch.

Matthieu


Kyungmin Park a écrit :
> Hi,
> 
> Not good news. This patch make a hang at probe time.
> it's tested against commit 7e27d6e778cd87b6f2415515d7127eba53fe5d02
> Author: Linus Torvalds <torvalds@linux-foundation.org>
> Date:   Fri Jun 11 19:14:04 2010 -0700
> 
>     Linux 2.6.35-rc3
> 
> Thank you,
> Kyungmin Park
> 
> On Thu, Jun 17, 2010 at 6:07 PM, Matthieu CASTET
> <matthieu.castet@parrot.com> wrote:
>> sdhci code got tasklets (sdhci_tasklet_card and sdhci_tasklet_finish),
>> that does :
>> {
>> spin_lock_irqsave
>>
>> if (cond) {
>> sdhci_reset
>> sdhci_reset
>> }
>>
>> spin_unlock_irqrestore
>> }
>>
>> sdhci_reset {
>> ...
>> while (read_reg) {
>> if (timeout == 0)
>>   break;
>> timeout--;
>> mdelay(1);
>> }
>> ...
>> }
>>
>>
>> The problem is that sdhci_reset [1] does busy pooling (with a granularity of
>> 1 ms) on a register up to a timeout of 100 ms.
>>
>> With the current code, we got irq off during 2*1ms. With the attached patch
>> we reduce irq off to 30 us.
>>
>> Note that worst case 100 ms irq off still exist.
>>
>> Signed-off-by: Matthieu CASTET <matthieu.castet@parrot.com>
>>
>>