Re: [PATCH 2/5] sata_mv clean up mv_stop_edma usage

[Jeff Garzik <jgarzik@pobox.com>]

Mark Lord wrote:
> Tejun Heo wrote:
>> Hello, Mark.
>>
>> Mark Lord wrote:
>>> -    /* now properly wait for the eDMA to stop */
>>> -    for (i = 1000; i > 0; i--) {
>>> -        reg = readl(port_mmio + EDMA_CMD_OFS);
>>> +    /* Wait for the chip to confirm eDMA is off. */
>>> +    for (i = 10000; i > 0; i--) {
>>> +        u32 reg = readl(port_mmio + EDMA_CMD_OFS);
>>>         if (!(reg & EDMA_EN))
>>> -            break;
>>> -
>>> -        udelay(100);
>>> -    }
>>> -
>>> -    if (reg & EDMA_EN) {
>>> -        ata_port_printk(ap, KERN_ERR, "Unable to stop eDMA\n");
>>> -        err = -EIO;
>>> +            return 0;
>>> +        udelay(10);
>>
>> Unless the hardware calls for really short polling interval, I think 
>> it's generally better to limit polling with jiffies and using msleep() 
>> instead of delays.
> ..
> 
> Oh, absolutely.  I was just leaving Jeff's (?) original udelay() in there
> for now, to avoid another possible failure while testing the new stuff.
> 
> But if we can *guarantee* that .qc_issue and .port_stop are
> always invoked only from thread context, then.. no problemo.

qc_issue is inside spin_lock_irqsave()