Hello. Clean up config_drive_for_dma() from the useless code: - there's no need for PIO fallback here since this is done by the caller, piix_config_drive_xfer_rate(); - there's no need for MWDMA mode 0 check, since this mode is not supported by the driver (hwif->mwdma_mask == 0x6), and hence can't be selected by ide_dma_speed(). Also, while at it, simplify piix_config_drive_xfer_rate() a bit. MBR, Sergei Signed-off-by: Sergei Shtylyov <sshtylyov@xxxxxxxxxxxxx>
Index: linus/drivers/ide/pci/piix.c =================================================================== --- linus.orig/drivers/ide/pci/piix.c +++ linus/drivers/ide/pci/piix.c @@ -4,10 +4,11 @@ * Copyright (C) 1998-1999 Andrzej Krzysztofowicz, Author and Maintainer * Copyright (C) 1998-2000 Andre Hedrick <andre@xxxxxxxxxxxxx> * Copyright (C) 2003 Red Hat Inc <alan@xxxxxxxxxx> + * Copyright (C) 2006 MontaVista Software, Inc. <source@xxxxxxxxxx> * * May be copied or modified under the terms of the GNU General Public License * - * PIO mode setting function for Intel chipsets. + * PIO mode setting function for Intel chipsets. * For use instead of BIOS settings. * * 40-41 @@ -25,7 +26,7 @@ * sitre = word42 & 0x4000; secondary * * 44 8421|8421 hdd|hdb - * + * * 48 8421 hdd|hdc|hdb|hda udma enabled * * 0001 hda @@ -73,8 +74,6 @@ * PIIX4 errata #15 - Must not read control registers * during a PIO transfer * 440MX errata #13 - As PIIX4 errata #15 - * ICH2 errata #21 - DMA mode 0 doesn't work right - * ICH0/1 errata #55 - As ICH2 errata #21 * ICH2 spec c #9 - Extra operations needed to handle * drive hotswap [NOT YET SUPPORTED] * ICH2 spec c #20 - IDE PRD must not cross a 64K boundary @@ -333,56 +332,24 @@ static int piix_tune_chipset (ide_drive_ } /** - * 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 * * Set up a PIIX interface channel for the best available speed. - * We prefer UDMA if it is available and then MWDMA. If DMA is - * not available we switch to PIO and return 0. + * We prefer UDMA if it is available and then MWDMA. If DMA is + * not available we return 0. */ 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 */ - - if (!speed || no_piix_dma) { - u8 tspeed = ide_get_best_pio_mode(drive, 255, 5, NULL); - speed = piix_dma_2_pio(XFER_PIO_0 + tspeed); - } + + /* + * If no DMA speed was available or the chipset has DMA bugs + * then disable DMA and use PIO + */ + if (!speed || no_piix_dma) + return 0; (void) piix_tune_chipset(drive, speed); return ide_dma_enable(drive); @@ -405,10 +372,8 @@ static int piix_config_drive_xfer_rate ( if ((id->capability & 1) && drive->autodma) { - if (ide_use_dma(drive)) { - if (piix_config_drive_for_dma(drive)) - return hwif->ide_dma_on(drive); - } + if (ide_use_dma(drive) && piix_config_drive_for_dma(drive)) + return hwif->ide_dma_on(drive); goto fast_ata_pio;