linux-kernel - [PATCH 5/8] resend cciss: disable DMA prefetch on P600

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Date:	Fri, 3 Nov 2006 09:54:12 -0600
From:	"Mike Miller (OS Dev)" <mikem@...rdog.cca.cpqcorp.net>
To:	akpm@...l.org, jens.axboe@...cle.com
Cc:	linux-kernel@...r.kernel.org, linux-scsi@...r.kernel.org
Subject: [PATCH 5/8] resend cciss: disable DMA prefetch on P600

PATCH 5 of 8 resend

This patch unconditionally disables DMA prefetch on the P600 controller. A
bug in the ASIC may result in prefetching either beyond the end of memory
or to fall off into a memory hole.
Please consider this for inclusion.

Thanks,
mikem

Signed-off-by: Mike Miller <mike.miller@...com>

 cciss.c     |   13 +++++++++++++
 cciss_cmd.h |    1 +
 2 files changed, 14 insertions(+)
--------------------------------------------------------------------------------
diff -urNp linux-2.6-p00004/drivers/block/cciss.c linux-2.6-p00005/drivers/block/cciss.c
--- linux-2.6-p00004/drivers/block/cciss.c	2006-10-31 15:20:25.000000000 -0600
+++ linux-2.6-p00005/drivers/block/cciss.c	2006-11-03 09:43:55.000000000 -0600
@@ -2997,6 +2997,19 @@ static int cciss_pci_init(ctlr_info_t *c
 	}
 #endif
 
+	{
+		/* Disabling DMA prefetch for the P600
+		 * An ASIC bug may result in a prefetch beyond
+		 * physical memory.
+		 */
+		__u32 dma_prefetch
+		if(board_id == 0x3225103C) {
+			dma_prefetch = readl(c->vaddr + I2O_DMA1_CFG);
+			dma_prefetch |= 0x8000;
+			writel(dma_prefetch, c->vaddr + I2O_DMA1_CFG);
+		}
+	}
+
 #ifdef CCISS_DEBUG
 	printk("Trying to put board into Simple mode\n");
 #endif				/* CCISS_DEBUG */
diff -urNp linux-2.6-p00004/drivers/block/cciss_cmd.h linux-2.6-p00005/drivers/block/cciss_cmd.h
--- linux-2.6-p00004/drivers/block/cciss_cmd.h	2006-10-31 14:31:05.000000000 -0600
+++ linux-2.6-p00005/drivers/block/cciss_cmd.h	2006-10-31 15:43:18.000000000 -0600
@@ -55,6 +55,7 @@
 #define I2O_INT_MASK            0x34
 #define I2O_IBPOST_Q            0x40
 #define I2O_OBPOST_Q            0x44
+#define I2O_DMA1_CFG		0x214
 
 //Configuration Table
 #define CFGTBL_ChangeReq        0x00000001l
-
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