[PATCH] cciss: disable DMA prefetch on P600

Unconditionally disable DMA prefetch on the P600 controller.  An ASIC bug may
result in prefetching beyond the end of physical memory.
Signed-off-by: NMike Miller <mike.miller@hp.com>
Acked-by: NJens Axboe <jens.axboe@oracle.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

drivers/block/cciss.c

@@ -3003,6 +3003,17 @@ static int cciss_pci_init(ctlr_info_t *c, struct pci_dev *pdev)
 	}
 #endif
 
+	/* Disabling DMA prefetch for the P600
+	 * An ASIC bug may result in a prefetch beyond
+	 * physical memory.
+	 */
+	if(board_id == 0x3225103C) {
+		__u32 dma_prefetch;
+		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 */

drivers/block/cciss_cmd.h

@@ -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