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pata_pdc202xx_old: fix UDMA mode for Promise UDMA33 cards

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commit a75032e877 upstream.

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 <rmk@arm.linux.org.uk>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Bartlomiej Zolnierkiewicz
2010-02-13 14:35:53 +01:00
committed by Greg Kroah-Hartman
parent 606fa05a76
commit 526c2b2bdf
1 changed files with 12 additions and 1 deletions
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13
drivers/ata/pata_pdc202xx_old.c
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@@ -2,7 +2,7 @@
* pata_pdc202xx_old.c - Promise PDC202xx PATA for new ATA layer
* (C) 2005 Red Hat Inc
* Alan Cox <alan@lxorguk.ukuu.org.uk>
* (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 = {