Mark Lord wrote:
> Tejun Heo wrote:
>> ..
>> Then, PACKET_IDENTIFY after configuring transfer mode fails with
>> -ENOENT.  Meaning it saw (status & (ATA_BUSY|ATA_DRQ|ATA_ERR|ATA_DF)) ==
>> 0 in HSM_ST.
> ..
>> So, PATA gurus, can you bless us with enlightenment?  :-)
> 
> Heh.. guaranteeing detection of all the strange implementations out there
> is part black magic.
> 
> But the simple thing to do here is, just for fun, hack the code
> to do the infamous 50 millisecond hard wait before issuing the
> PACKET_IDENTIFY.
> If that fixes it, then it's just a matter of tuning to discover the real
> amount of delay required, and a nicer way of doing the delay.

Okay.

> Also, zero out the features register before issuing PACKET_IDENTIFY,
> if the code isn't already doing that.

Okay.

> After the drive asserts BUSY, and later deasserts BUSY,
> there might be a slight delay before the drive asserts DRQ.
> So, it is possible for the status to read zeros in the important bits.
> 
> My suggestion is to wait up to the infamous 50 milliseconds again here,
> if needed.

Okay, the attached patch does what Mark suggested.  Art, can you please
give it a shot and report dmesg?  My thanks for sticking around till now.

-- 
tejun