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

[Sergei Shtylyov <sshtylyov@ru.mvista.com>]

Hello.

Mark Lord wrote:

>>>> 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?
>>
>> We already do 1, 2 and 3.  The problem with phantom device is that the
>> existent device on the channel replies to acesses to the other
>> non-existent device and the NODEV_HINT detection is the last line of
>> defense which successfully evades all the other mechanisms.  And now
>> we have this controller/device combination which successfully tricks
>> it too.  :-(
> ..
>
> Mmm.. but he's using "really old ata_piix" hardware, as in what Intel
> once called the "Triton" (or Triton II) chipset.

   The "original Triton" IDE is supported by pata_oldpiix.

>   Which I wrote support
> for in drivers/ide, way back when.. and we never had this problem.

   The support for the "original Triton" is drivers/ide/ is still broken 
after all these years. The driver assumes that the slave IDE timing 
register always present -- which the origina 82371FB didn't have. :-(

WBR, Sergei