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NAME
       ata_mmio_devchk - PATA device presence detection


SYNOPSIS
       unsigned int ata_mmio_devchk  (struct ata_port * ap,
                                        unsigned int device);


ARGUMENTS
       ap     ATA channel to examine

       device Device to examine (starting at zero)


DESCRIPTION
       This technique  was  originally  described  in  Hale  Landis’s  ATADRVR
       (www.ata-atapi.com), and later found its way into the ATA/ATAPI spec.

       Write  a  pattern  to  the  ATA  shadow  registers,  and if a device is
       present, it will respond by correctly storing and echoing back the  ATA
       shadow register contents.


LOCKING
       caller.


AUTHOR
       Jeff Garzik.