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    SubjectRe: Quick question about libata and hdparm
    Date
    On Monday 20 April 2009 19:35:27 Rogério Brito wrote:
    > Hi, Jeff.
    >
    > On Apr 19 2009, Jeff Garzik wrote:
    > > Well, it's supposed to reduce speed in several circumstances... just
    > > not Michael's. :)
    >
    > Well, I'll take that as a yes. :-)
    >
    > Can you comment on the dmesg log attached? I'd like to, at least,
    > understand what is happening, since I'm starting to consider using
    > libata with all my computers.
    >
    > This computer, in particular, uses an IDE drive with a 40 ribbon cable
    > (and, thus, no UDMA/66). The cable is well put (checked two times
    > already) and I believe that everything is OK with this cable, since I
    > substituted it was already substituting one that gave me the same
    > results.

    DISCLAIMER: I'm not handling this bugreport, this is best
    done by pata_pdc202xx_old Maintainer or libata Maintainer.

    Rogério, if the issue is reproducible you can give this patch a try...

    From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
    Subject: [PATCH] pata_pdc202xx_old: fix UDMA33 handling

    The original driver doesn't use 66 MHz clock for UDMA33.

    [ The alternative solution would be to adjust UDMA33 timings
    for 66 MHz clock but I think that it is safer to stick with
    old & tested behavior for now. ]

    Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
    ---
    drivers/ata/pata_pdc202xx_old.c | 6 +++---
    1 file changed, 3 insertions(+), 3 deletions(-)

    Index: b/drivers/ata/pata_pdc202xx_old.c
    ===================================================================
    --- a/drivers/ata/pata_pdc202xx_old.c
    +++ b/drivers/ata/pata_pdc202xx_old.c
    @@ -2,7 +2,7 @@
    * pata_pdc202xx_old.c - Promise PDC202xx PATA for new ATA layer
    * (C) 2005 Red Hat Inc
    * Alan Cox <alan@lxorguk.ukuu.org.uk>
    - * (C) 2007 Bartlomiej Zolnierkiewicz
    + * (C) 2007,2009 Bartlomiej Zolnierkiewicz
    *
    * Based in part on linux/drivers/ide/pci/pdc202xx_old.c
    *
    @@ -158,7 +158,7 @@ static void pdc2026x_bmdma_start(struct
    u32 len;

    /* Check we keep host level locking here */
    - if (adev->dma_mode >= XFER_UDMA_2)
    + if (adev->dma_mode > XFER_UDMA_2)
    iowrite8(ioread8(clock) | sel66, clock);
    else
    iowrite8(ioread8(clock) & ~sel66, clock);
    @@ -212,7 +212,7 @@ static void pdc2026x_bmdma_stop(struct a
    iowrite8(ioread8(clock) & ~sel66, clock);
    }
    /* Flip back to 33Mhz for PIO */
    - if (adev->dma_mode >= XFER_UDMA_2)
    + if (adev->dma_mode > XFER_UDMA_2)
    iowrite8(ioread8(clock) & ~sel66, clock);
    ata_bmdma_stop(qc);
    pdc202xx_set_piomode(ap, adev);
    --
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