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

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Message-Id: <1162572135.3160.2.camel@laptopd505.fenrus.org>
Date:	Fri, 03 Nov 2006 17:42:15 +0100
From:	Arjan van de Ven <arjan@...radead.org>
To:	"Mike Miller (OS Dev)" <mikem@...rdog.cca.cpqcorp.net>
Cc:	akpm@...l.org, jens.axboe@...cle.com, linux-kernel@...r.kernel.org,
	linux-scsi@...r.kernel.org
Subject: Re: [PATCH 5/8] resend cciss: disable DMA prefetch on P600

On Fri, 2006-11-03 at 09:54 -0600, Mike Miller (OS Dev) wrote:
> 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);
> +		}
> +	}
> +

if you remove the if() you might as well also remove the {}'s ;)

-- 
if you want to mail me at work (you don't), use arjan (at) linux.intel.com
Test the interaction between Linux and your BIOS via http://www.linuxfirmwarekit.org

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