[PATCH] pata_cmd64x: fix overclocking of UDMA0-2 modes

[Bartlomiej Zolnierkiewicz]

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: sta...@kernel.org
Signed-off-by: Bartlomiej Zolnierkiewicz <bzol...@gmail.com>
---
it is patch #116 in my local working queue but I thought it would
be nice to get it upstream ahead of other patches..

drivers/ata/pata_cmd64x.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

Index: b/drivers/ata/pata_cmd64x.c
===================================================================
--- a/drivers/ata/pata_cmd64x.c
+++ b/drivers/ata/pata_cmd64x.c
@@ -254,7 +254,7 @@ static void cmd64x_set_dmamode(struct at
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 */
--
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[Jeff Garzik]

On 12/20/2009 01:22 PM, Bartlomiej Zolnierkiewicz wrote:
>
> 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: sta...@kernel.org
> Signed-off-by: Bartlomiej Zolnierkiewicz<bzol...@gmail.com>
> ---
> it is patch #116 in my local working queue but I thought it would
> be nice to get it upstream ahead of other patches..
>
> drivers/ata/pata_cmd64x.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)

applied