Re: [PATCH] Re: 2.6.17-rc5-git1: regression: resume from suspend(RAM) fails: libata issue

[Mark Lord <liml@rtr.ca>]

Jeff Garzik wrote:
> Linus Torvalds wrote:
>> diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
>> index fa476e7..6ccfbc9 100644
>> --- a/drivers/scsi/libata-core.c
>> +++ b/drivers/scsi/libata-core.c
>> @@ -4296,6 +4296,13 @@ static int ata_start_drive(struct ata_po
>>   */
>>  int ata_device_resume(struct ata_port *ap, struct ata_device *dev)
>>  {
>> +    /*
>> +     * Wait for BUSY to go away for up to 2 seconds,
>> +     * and then try to wait for idle (up to 1 msec)
>> +     */
>> +    ata_busy_wait(ap, ATA_BUSY, 200000);
>> +    ata_wait_idle(ap);
> 
> I don't object, but ata_wait_idle() is completely pointless.
> 
> ata_wait_idle() has nothing to do with DRDY.  It waits until both BSY 
> and DRQ are clear.  See:
>> u8 status = ata_busy_wait(ap, ATA_BUSY | ATA_DRQ, 1000);

Good point.  But I think Linus just mucked up his explanation,
as Jens has never used a patch to wait for DRDY, but rather only
to wait for DRQ to clear, same as the latest Linus patch does
(but in a different sequence from Linus's).

Good thing too, as waiting for DRDY would be silly for ATAPI drives.

Cheers