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    SubjectRe: [RFT] major libata update
    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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