From: Mike Miller Unconditionally disable DMA prefetch on the P600 controller. An ASIC bug may result in prefetching beyond the end of physical memory. Signed-off-by: Mike Miller Acked-by: Jens Axboe Signed-off-by: Andrew Morton --- drivers/block/cciss.c | 11 +++++++++++ drivers/block/cciss_cmd.h | 1 + 2 files changed, 12 insertions(+) diff -puN drivers/block/cciss.c~cciss-disable-dma-prefetch-on-p600 drivers/block/cciss.c --- a/drivers/block/cciss.c~cciss-disable-dma-prefetch-on-p600 +++ a/drivers/block/cciss.c @@ -2997,6 +2997,17 @@ 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. + */ + 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 */ diff -puN drivers/block/cciss_cmd.h~cciss-disable-dma-prefetch-on-p600 drivers/block/cciss_cmd.h --- a/drivers/block/cciss_cmd.h~cciss-disable-dma-prefetch-on-p600 +++ a/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 _