Re: [RFT] major libata update

[Tejun Heo <htejun@gmail.com>]

Albert Lee wrote:
> > To sum up, it happens when the master slot is occupied by an ATAPI
> > device and the corresponding slave slot is empty.  The slave slot
> > reports ATAPI signature (probably duplicated from the master) and passes
> > all legacy presence test thus resulting in timeout on IDENTIFY.
>
> This problem was seen with PATA Promise 20275 adapter + IBM DVD-RAM drive.
> Single master device configuration, no slave device.
> The master device acts as slave and creates a phantom slave device.
> (http://marc.theaimsgroup.com/?l=linux-ide&m=113151315602979&w=2)
>
> The problem was later fixed by Tejun's ata_exec_internal() patch:
> (http://marc.theaimsgroup.com/?l=linux-ide&m=113455450809405&w=2)
> After the patch, the phantom device is finally detected by ata_dev_identify().
>
> Libata uses polling PIO for IDENTIFY DEVICE before this major update.
> The polling PIO finds something wrong when it reads a 0x00 device status.
> So, the phantom device is detected quite quickly.
>
> With irq-driven PIO, maybe the phantom device is only detected after time-out.
> So it takes longer (30 secs) to detect the phantom device.
>
> No good idea how to fix this. Maybe read more registers to see whether the
> phantom device can be detected early before the IDENTIFY DEVICE.

Does the Promise controller show the ghosting problem again with the 
recent updates?  ata_piix can be fixed by using PCS present bits.  I 
don't know about Promise though.

--
tejun
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