[PATCH] hpt366: fix HPT370 DMA timeouts

[PATCH] hpt366: fix HPT370 DMA timeouts

[Sergei Shtylyov]

The big driver change in 2.4.19-rc1 introduced a regression for many HPT370[A]
chips -- DMA stopped to work completely, only causing endless timeouts...

The culprit has been identified (at last!): it turned to be the code resetting
the DMA state machine before each transfer. Stop doing it now as this counter-
measure has clearly caused more harm than good.

This should fix the kernel.org bug #7703.

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>

---
This patch is against the recent Linus' tree.
It should go into all stable kernels as it fixes post-2.4.18 (!) regression.

 drivers/ide/hpt366.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletion(-)

Index: linux-2.6/drivers/ide/hpt366.c
===================================================================
--- linux-2.6.orig/drivers/ide/hpt366.c
+++ linux-2.6/drivers/ide/hpt366.c
@@ -114,6 +114,8 @@
  *   the register setting lists into the table indexed by the clock selected
  * - set the correct hwif->ultra_mask for each individual chip
  * - add Ultra and MW DMA mode filtering for the HPT37[24] based SATA cards
+ * - stop resetting HPT370's state machine before each DMA transfer as that has
+ *   caused more harm than good
  *	Sergei Shtylyov, <sshtylyov@ru.mvista.com> or <source@mvista.com>
  */
 
@@ -133,7 +135,7 @@
 #define DRV_NAME "hpt366"
 
 /* various tuning parameters */
-#define HPT_RESET_STATE_ENGINE
+#undef	HPT_RESET_STATE_ENGINE
 #undef	HPT_DELAY_INTERRUPT
 
 static const char *quirk_drives[] = {

Re: [PATCH] hpt366: fix HPT370 DMA timeouts

[Bartlomiej Zolnierkiewicz]

On Tuesday 07 April 2009 18:09:32 Sergei Shtylyov wrote:
> The big driver change in 2.4.19-rc1 introduced a regression for many HPT370[A]
> chips -- DMA stopped to work completely, only causing endless timeouts...
> 
> The culprit has been identified (at last!): it turned to be the code resetting
> the DMA state machine before each transfer. Stop doing it now as this counter-
> measure has clearly caused more harm than good.
> 
> This should fix the kernel.org bug #7703.
> 
> Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>

Wow!

applied