linux-kernel - [63/68] pata_pdc202xx_old: fix UDMA mode for Promise UDMA33 cards

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Date:	Fri, 24 Sep 2010 09:32:27 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Bartlomiej Zolnierkiewicz <bzolnier@...il.com>,
	Jeff Garzik <jgarzik@...hat.com>
Subject: [63/68] pata_pdc202xx_old: fix UDMA mode for Promise UDMA33 cards

2.6.32-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Bartlomiej Zolnierkiewicz <bzolnier@...il.com>

commit a75032e8772d13dab5e3501413d7e14a148281b4 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@....linux.org.uk>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@...il.com>
Signed-off-by: Jeff Garzik <jgarzik@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 drivers/ata/pata_pdc202xx_old.c |   13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

--- 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 <alan@...rguk.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
 	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 pdc202
 	.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 = {


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