From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH 2/3] qla1280: user pci_map_single Date: Fri, 18 Feb 2005 11:21:31 +0100 Message-ID: <20050218102131.GA2941@lst.de> References: <20050210160026.GB8743@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Received: from verein.lst.de ([213.95.11.210]:36760 "EHLO mail.lst.de") by vger.kernel.org with ESMTP id S261329AbVBRKVf (ORCPT ); Fri, 18 Feb 2005 05:21:35 -0500 Content-Disposition: inline In-Reply-To: Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Jes Sorensen Cc: jejb@steeleye.com, linux-scsi@vger.kernel.org On Fri, Feb 18, 2005 at 04:48:00AM -0500, Jes Sorensen wrote: > Christoph, > > When pci_map_page was originally introduced it was meant to deprecate > pci_map_single, at least thats what my memory tells me. No, it's for rather different uses. pci_map_page would be nice to get rid of in favour of pci_map_sg OTOH.. > If pci_map_single is suddenly recommended again we can change it back > to that, but I don't really see the gain. it's a micro-speedup by avoiding totally useless address arithmetics. You first convert a buffer to page + offset and then it needs to be converted back, e.g. in include/asm-ia64/dma-mapping.h: #define dma_map_page(dev, pg, off, size, dir) \ dma_map_single(dev, page_address(pg) + (off), (size), (dir)) (pci_map_page is mapped to dma_map_page)