From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: [PATCH] dc395x: Fix support for highmem Date: Wed, 16 Mar 2005 18:04:17 +0100 Message-ID: <20050316170417.GY7842@suse.de> References: <200503160209.j2G29cAf010870@hera.kernel.org> <20050316075839.GC7842@suse.de> <1110986016.5771.3.camel@mulgrave> <20050316160447.GU7842@suse.de> <20050316164806.GO21986@parcelfarce.linux.theplanet.co.uk> <20050316165338.GX7842@suse.de> <20050316170259.GA25056@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Received: from ns.virtualhost.dk ([195.184.98.160]:2734 "EHLO virtualhost.dk") by vger.kernel.org with ESMTP id S262682AbVCPRE1 (ORCPT ); Wed, 16 Mar 2005 12:04:27 -0500 Content-Disposition: inline In-Reply-To: <20050316170259.GA25056@infradead.org> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Christoph Hellwig Cc: Matthew Wilcox , James Bottomley , SCSI Mailing List , g.liakhovetski@gmx.de On Wed, Mar 16 2005, Christoph Hellwig wrote: > On Wed, Mar 16, 2005 at 05:53:39PM +0100, Jens Axboe wrote: > > The list doesn't really need dma mapping at that point, the problem here > > is that the driver needs to punt to pio mode because of foo. So calling > > pci/dma_map_* is pointless, since the CPU will have to do the transfer > > anyways. What the driver is really looking for at this point, is a way > > to map the pages in the sglist to a virtual address. > > Given that there's quite a few cases of this "problem" it would be nice > to have common helpers for it. Especially as it's really difficult when > we allow merging of sg list entries I thought about that when writing the above, but is there really more than one case for SCSI drivers? If there is, sure lets add the helpers. But I would consider it a quite rare occurence, I've never seen it before. -- Jens Axboe