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

[Mark Lord <liml@rtr.ca>]

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.

> Also, mv_stop_edma() skips actual operation if EDMA_EN isn't set, which 
> I think is the correct way to do it in hot paths but I think it's better 
> to stop the edma engine unconditionally prior to reset as that's where 
> we try to bring the controller back into senses.
..

Harmless change.  FITNR.

Thanks