Re: ISP1760 driver crashes

[Jens Axboe]

On Thu, Nov 20 2008, Alan Stern wrote:
> On Thu, 20 Nov 2008, FUJITA Tomonori wrote:
> 
> > We have been used 4GB for long time if dma_mask is zero (I guess we
> > use 4GB as kinda the default dma address limit at several places). The
> > majority of drivers (such as pci) sets properly dev->dma_mask so the
> > patch might not change anything but suddenly changing the
> > long-standing rule in an odd way (use BLK_BOUNCE_HIGH if dma_mask is
> > zero) doesn't sound a good idea to me.
> > 
> > Why not calling blk_queue_bounce_limit() in the slave_configure hook?
> > I think that it's the common way for SCSI LLDs with odd bounce limit.
> 
> Thomas, here's a patch to do what Tomonori suggests.  Try replacing the 
> old patch with this one.
> 
> Alan Stern
> 
> 
> Index: usb-2.6/drivers/usb/storage/scsiglue.c
> ===================================================================
> --- usb-2.6.orig/drivers/usb/storage/scsiglue.c
> +++ usb-2.6/drivers/usb/storage/scsiglue.c
> @@ -129,6 +129,14 @@ static int slave_configure(struct scsi_d
>  					      max_sectors);
>  	}
>  
> +	/* Some USB host controllers can't do DMA; they have to use PIO.
> +	 * They indicate this by setting their dma_mask to NULL.  For
> +	 * such controllers we need to make sure the block layer sets
> +	 * up bounce buffers in addressable memory.
> +	 */
> +	if (!us->pusb_dev->bus->controller->dma_mask)
> +		blk_queue_bounce_limit(sdev->request_queue, BLK_BOUNCE_HIGH);
> +
>  	/* We can't put these settings in slave_alloc() because that gets
>  	 * called before the device type is known.  Consequently these
>  	 * settings can't be overridden via the scsi devinfo mechanism. */
> 

That looks like a good fix. You can add my Acked-by: to that, if you
wish.

-- 
Jens Axboe

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