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    SubjectRe: [patch ide-dev 7/9] convert disk flush functions to use REQ_DRIVE_TASKFILE
    Date
    On Monday 28 February 2005 16:12, Tejun Heo wrote:
    > Bartlomiej Zolnierkiewicz wrote:
    > > On Sunday 27 February 2005 05:51, Tejun Heo wrote:
    > >
    > >> Hello, Bartlomiej,
    > >>
    > >>On Thu, Feb 24, 2005 at 03:45:39PM +0100, Bartlomiej Zolnierkiewicz wrote:
    > >>
    > >>>Original patch from Tejun Heo <htejun@gmail.com>,
    > >>>ported over recent IDE changes by me.
    > >>>
    > >>>* teach ide_tf_get_address() about CHS
    > >>
    > >> IMHO, as patch #4 moves LBA/CHS selection into taskfile, I think
    > >>using taskfile->device to determine whether LBA or CHS is used instead
    > >>of drive->select makes more sense.
    > >>
    > >>
    > >>>* use ide_tf_get_address() and remove ide_get_error_location()
    > >>
    > >> IIRC, error responses for WIN_FLUSH_CACHE is in CHS if the LBA bit in
    > >>the device register is zero; likewise, in LBA if the LBA bit is one.
    > >>I don't know if drives can change the LBA bit when posting error
    > >>result. The original code reads back the device register on error to
    > >>determine whether to interpret the error response in CHS or LBA.
    > >>(ATA/ATAPI-6 isn't clear on this issue. Is ATA/ATAPI-7 updated?)
    > >
    > >
    > > The thing is that LBA bit is marked as "na" for FLUSH CACHE
    > > in all ATA/ATAPI drafts that I've seen.
    > >
    >
    > Yeah, and nothing is mentioned about the LBA bit in the normal output
    > description even though the lcyl, hcyl.. registers are described to be
    > in either form of CHS or LBA. Strange...
    >
    > >
    > >> This change combined with patch #2/#5 can make error address
    > >>calculation wrong on LBA28 drives. I think setting the LBA bit in the
    > >>device register according to the drive's addressing mode in
    > >>ide_task_init_flush() and use taskfile->device in ide_tf_get_address()
    > >>should fix the problem.
    > >
    > >
    > > I will change the code to set LBA bit, it shouldn't hurt. :-)
    >
    > IMHO, there can be cases where just setting the LBA bit isn't enough.
    > Theoretically, drives can report CHS and clear the LBA bit in the
    > device register even when the LBA bit was set when the command was
    > issued. Maybe the intention of the original code was to handle
    > something like this?

    /me suspects that disks that support LBA always report LBA and disks
    that use only CHS always report CHS but this is pure speculation
    -
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