[PATCH] PIIX: remove check for broken MW DMA mode 0

There's no need to check in piix_config_drive_for_dma() for broken MW DMA
mode 0 as this mode is not supported by the driver (it sets
hwif->mwdma_mask to 0x6), and hence can't be selected by ide_dma_speed().

(Alan sayeth "Probably right but if not you've got a subtle corruptor.  Should
at least stick a BUG_ON mode 0 setting right close when the mode is set.")

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Acked-by: Bartlomiej Zolnierkiewicz <B.Zolnierkiewicz@elka.pw.edu.pl>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/ide/pci/piix.c

@@ -352,33 +352,6 @@ static int piix_tune_chipset (ide_drive_t *drive, u8 xferspeed)
 	return (ide_config_drive_speed(drive, speed));
 }
 
-/**
- *	piix_faulty_dma0		-	check for DMA0 errata
- *	@hwif: IDE interface to check
- *
- *	If an ICH/ICH0/ICH2 interface is is operating in multi-word
- *	DMA mode with 600nS cycle time the IDE PIO prefetch buffer will
- *	inadvertently provide an extra piece of secondary data to the primary
- *	device resulting in data corruption.
- *
- *	With such a device this test function returns true. This allows
- *	our tuning code to follow Intel recommendations and use PIO on
- *	such devices.
- */
-
-static int piix_faulty_dma0(ide_hwif_t *hwif)
-{
-	switch(hwif->pci_dev->device)
-	{
-		case PCI_DEVICE_ID_INTEL_82801AA_1:	/* ICH */
-		case PCI_DEVICE_ID_INTEL_82801AB_1:	/* ICH0 */
-		case PCI_DEVICE_ID_INTEL_82801BA_8:	/* ICH2 */
-		case PCI_DEVICE_ID_INTEL_82801BA_9:	/* ICH2 */
-			return 1;
-	}
-	return 0;
-}
-
 /**
  *	piix_config_drive_for_dma	-	configure drive for DMA
  *	@drive: IDE drive to configure
@@ -391,10 +364,6 @@ static int piix_faulty_dma0(ide_hwif_t *hwif)
 static int piix_config_drive_for_dma (ide_drive_t *drive)
 {
 	u8 speed = ide_dma_speed(drive, piix_ratemask(drive));
-
-	/* Some ICH devices cannot support DMA mode 0 */
-	if(speed == XFER_MW_DMA_0 && piix_faulty_dma0(HWIF(drive)))
-		speed = 0;
 
 	/* If no DMA speed was available or the chipset has DMA bugs
 	   then disable DMA and use PIO */