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pata_cmd64x: fix overclocking of UDMA0-2 modes

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adev->dma_mode stores the transfer mode value not UDMA mode number
so the condition in cmd64x_set_dmamode() is always true and the higher
UDMA clock is always selected.  This can potentially result in data
corruption when UDMA33 device is used, when 40-wire cable is used or
when the error recovery code decides to lower the device speed down.

The issue was introduced in the commit 6a40da0 ("libata cmd64x: whack
into a shape that looks like the documentation") which goes back to
kernel 2.6.20.

Cc: stable@kernel.org
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
This commit is contained in:
Bartlomiej Zolnierkiewicz 2009-12-20 19:22:33 +01:00 committed by Jeff Garzik
parent 06393afde3
commit 509426bd46
1 changed files with 1 additions and 1 deletions
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2
drivers/ata/pata_cmd64x.c
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@ -219,7 +219,7 @@ static void cmd64x_set_dmamode(struct ata_port *ap, struct ata_device *adev)
regU |= udma_data[adev->dma_mode - XFER_UDMA_0] << shift;
/* Merge the control bits */
regU |= 1 << adev->devno; /* UDMA on */
if (adev->dma_mode > 2) /* 15nS timing */
if (adev->dma_mode > XFER_UDMA_2) /* 15nS timing */
regU |= 4 << adev->devno;
} else {
regU &= ~ (1 << adev->devno); /* UDMA off */