Re: Not able to set DMA mode other than default using hdparm

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Pedanekar, Hemant wrote:

I am getting following error when trying to set DMA transfer mode as UDMA2 on latest DaVinci (DM6467) git kernel using hdparm (9.27 or older):

# ./hdparm -d1 -Xudma2  /dev/hda
/dev/hda:hda: UDMA/66 mode selected
 setting using_dma to 1 (on)
hda: UDMA/66 mode selected
 setting xfermode to 66 (UltraDMA mode2)
 HDIO_DRIVE_CMD(setxfermode) failed: Invalid argument
 using_dma     =  1 (on)

It seems DMA mode setting other than the default mode returns this error. That is, if I use "-Xudma4" in above command it returns success as UDMA4 is the default mode on DM6467.

I made following change which allows hdparm to set any supported DMA mode. Can anyone confirm if this is a hdparm compatibility (incorrect use of ioctl?) or the patch below indeed fixes the issue?

diff --git a/drivers/ide/ide-ioctls.c b/drivers/ide/ide-ioctls.c
index d3440b5..6e7ae2b 100644
--- a/drivers/ide/ide-ioctls.c
+++ b/drivers/ide/ide-ioctls.c
@@ -162,7 +162,7 @@ static int ide_cmd_ioctl(ide_drive_t *drive, unsigned long arg)
        if (tf->command == ATA_CMD_SET_FEATURES &&
            tf->feature == SETFEATURES_XFER &&
            tf->nsect >= XFER_SW_DMA_0) {
-               xfer_rate = ide_find_dma_mode(drive, XFER_UDMA_6);
+               xfer_rate = ide_find_dma_mode(drive, tf->nsect);
                if (xfer_rate != tf->nsect) {
                        err = -EINVAL;
                        goto abort;


Looks like the patch is correct, the following commit has introduced the mistake:

http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=a9c415090710a108edcd81b3392b90396f190a9a

   Could you resubmit your patch with proper description and sign-off?

MBR, Sergei
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