On 2012-04-03 22:08, Arnd Bergmann wrote:
>>> +static void ep93xx_pata_wait_for_iordy(void __iomem *base)
>>> +{
>>> + unsigned long deadline = jiffies + msecs_to_jiffies(1000);
>>> + while (!ep93xx_pata_check_iordy(base) &&
>>> + time_is_before_jiffies(deadline))
>>> + cpu_relax();
>>> +}
>
> Much better for a delay than the previous version. However, it's
> still a busy wait, which is bad for realtime behavior, especially
> since this can potentially take many milliseconds. If possible,
> it should have an msleep() or at least cond_resched() instead of
> the cpu_relax(). Obviously that will only work when no spinlocks
> are held.
>
Unfortunately, we can't use msleep() or cond_resched() here
- ep93xx_pata_wait_for_iordy() is called from interrupt handler.
Thanks,
RP
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