From a75032e8772d13dab5e3501413d7e14a148281b4 Mon Sep 17 00:00:00 2001 From: Bartlomiej Zolnierkiewicz Date: Sat, 13 Feb 2010 14:35:53 +0100 Subject: [PATCH] pata_pdc202xx_old: fix UDMA mode for Promise UDMA33 cards On Monday 04 January 2010 02:30:24 pm Russell King wrote: > Found the problem - getting rid of the read of the alt status register > after the command has been written fixes the UDMA CRC errors on write: > > @@ -676,7 +676,8 @@ void ata_sff_exec_command(struct ata_port *ap, const struct > ata_taskfile *tf) > DPRINTK("ata%u: cmd 0x%X\n", ap->print_id, tf->command); > > iowrite8(tf->command, ap->ioaddr.command_addr); > - ata_sff_pause(ap); > + ndelay(400); > +// ata_sff_pause(ap); > } > EXPORT_SYMBOL_GPL(ata_sff_exec_command); > > > This rather makes sense. The PDC20247 handles the UDMA part of the > protocol. It has no way to tell the PDC20246 to wait while it suspends > UDMA, so that a normal register access can take place - the 246 ploughs > on with the register access without any regard to the state of the 247. > > If the drive immediately starts the UDMA protocol after a write to the > command register (as it probably will for the DMA WRITE command), then > we'll be accessing the taskfile in the middle of the UDMA setup, which > can't be good. It's certainly a violation of the ATA specs. Fix it by adding custom ->sff_exec_command method for UDMA33 chipsets. Debugged-by: Russell King Signed-off-by: Bartlomiej Zolnierkiewicz Signed-off-by: Jeff Garzik --- drivers/ata/pata_pdc202xx_old.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/drivers/ata/pata_pdc202xx_old.c b/drivers/ata/pata_pdc202xx_old.c index 2f3c9bed63d9..8d25bd59a16e 100644 --- a/drivers/ata/pata_pdc202xx_old.c +++ b/drivers/ata/pata_pdc202xx_old.c @@ -2,7 +2,7 @@ * pata_pdc202xx_old.c - Promise PDC202xx PATA for new ATA layer * (C) 2005 Red Hat Inc * Alan Cox - * (C) 2007,2009 Bartlomiej Zolnierkiewicz + * (C) 2007,2009,2010 Bartlomiej Zolnierkiewicz * * Based in part on linux/drivers/ide/pci/pdc202xx_old.c * @@ -35,6 +35,15 @@ static int pdc2026x_cable_detect(struct ata_port *ap) return ATA_CBL_PATA80; } +static void pdc20246_exec_command(struct ata_port *ap, + const struct ata_taskfile *tf) +{ + DPRINTK("ata%u: cmd 0x%X\n", ap->print_id, tf->command); + + iowrite8(tf->command, ap->ioaddr.command_addr); + ndelay(400); +} + /** * pdc202xx_configure_piomode - set chip PIO timing * @ap: ATA interface @@ -271,6 +280,8 @@ static struct ata_port_operations pdc2024x_port_ops = { .cable_detect = ata_cable_40wire, .set_piomode = pdc202xx_set_piomode, .set_dmamode = pdc202xx_set_dmamode, + + .sff_exec_command = pdc20246_exec_command, }; static struct ata_port_operations pdc2026x_port_ops = {