Re: Fwd: [PATCH #upstream-fixes 1/4] libata: fix device iteration bugs

[Mark Lord <liml@rtr.ca>]

Tejun Heo wrote:
> (cc'ing Alan, Jeff and Mark).
> 
> Hello, guys.
> 
> Michael Guntsche wrote:
>> On Mon, 10 Nov 2008 15:52:02 +0900, Tejun Heo <tj@kernel.org> wrote:
>>> Hello,
>>> Looks like our phantom device detection logic is somehow broken.  Can
>>> you please apply the attached patch and report boot log?
>> Here is the output after adding the debug line. Hopefully this helps.
>>
>> ata_piix 0000:00:07.1: version 2.12
>> scsi0 : ata_piix
>> scsi1 : ata_piix
>> ata1: PATA max MWDMA2 cmd 0x1f0 ctl 0x3f6 bmdma 0xe800 irq 14
>> ata2: PATA max MWDMA2 cmd 0x170 ctl 0x376 bmdma 0xe808 irq 15
>> ata1.00: ATA-5: IC35L040AVER07-0, ER4OA45A, max UDMA/100
>> ata1.00: 66055248 sectors, multi 16: LBA
>> ata1.00: configured for MWDMA2
>> ata2.01: XXX status=0x1
>> ata2.01: failed to IDENTIFY (I/O error, err_mask=0x1)
>> ata2.01: XXX status=0x1
>> ata2.01: failed to IDENTIFY (I/O error, err_mask=0x1)
>> ata2.01: XXX status=0x1
>> ata2.01: failed to IDENTIFY (I/O error, err_mask=0x1)
>> ata2.00: ATAPI: SAMSUNG CD-R/RW SW-408B, M300, max MWDMA2
>> ata2.00: configured for MWDMA2
> 
> On Michael's real old ata_piix, somehow the ERR bit is set on phantom
> device defeating our phantom device detection logic.  We can relax
> phantom device condition but that increases the risk of misdetection on
> actual IDENTIFY errors.  Any ideas how we can nicely work around this one?
..

Mmm.. I'm way out of the loop on this now,
so please pardon me suggesting things known not to work, but..

1. Pay attention to ATA status register on this chipset?
   Eg. if it has BUSY, or reads 0x7f, then don't IDENTIFY?
2. Check for device signature before trying IDENTIFY?
3. Try a r/w test on the data register first, to see if there's
   really hardware attached to it?

Cheers