Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754107AbYKSRXY (ORCPT ); Wed, 19 Nov 2008 12:23:24 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752763AbYKSRXP (ORCPT ); Wed, 19 Nov 2008 12:23:15 -0500 Received: from pasmtpb.tele.dk ([80.160.77.98]:37593 "EHLO pasmtpB.tele.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752762AbYKSRXO (ORCPT ); Wed, 19 Nov 2008 12:23:14 -0500 Date: Wed, 19 Nov 2008 18:21:25 +0100 From: Jens Axboe To: Alan Stern Cc: Sebastian Andrzej Siewior , "Hommel, Thomas (GE EntSol, Intelligent Platforms)" , USB list , Kernel development list , James.Bottomley@HansenPartnership.com Subject: Re: ISP1760 driver crashes Message-ID: <20081119172125.GS26308@kernel.dk> References: <20081119153923.GR26308@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1667 Lines: 43 On Wed, Nov 19 2008, Alan Stern wrote: > On Wed, 19 Nov 2008, Jens Axboe wrote: > > > > --- usb-2.6.orig/drivers/scsi/scsi_lib.c > > > +++ usb-2.6/drivers/scsi/scsi_lib.c > > > @@ -1684,7 +1684,7 @@ static void scsi_request_fn(struct reque > > > u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost) > > > { > > > struct device *host_dev; > > > - u64 bounce_limit = 0xffffffff; > > > + u64 bounce_limit = BLK_BOUNCE_HIGH; > > > > > > if (shost->unchecked_isa_dma) > > > return BLK_BOUNCE_ISA; > > > > > > > The best solution is probably to either provide a "doesn't do highmem" > > in the scsi host template, or provide an appropriate DMA mask for the > > pci device to indicate it through that setting instead. > > The DMA mask is currently set to NULL. Is that not appropriate for a > device that can't do DMA? If not, then what would be appropriate? It's changing behaviour. There's no current rule that says if you don't have a dma mask set, we only do PIO (even if such a rule DOES make sense). Additionally, you don't HAVE to bounce for PIO. As I wrote earlier, it's perfectly feasible to use bio kmap'ings to do the transfer. > Also, is the patch above not correct? It'll certainly work in the sense that if you don't have a dma_mask set, you only get lowmem pages. Whether the new behaviour is something we want, not sure. Check with James what he thinks, it's his domain. -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/