From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefan Richter Subject: Re: question about passing physical address to lower level driver in scsi Date: Mon, 31 Oct 2011 13:22:09 +0100 Message-ID: <20111031132209.1d1ee186@stein> References: <20111030132821.4df33f1e@stein> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Received: from einhorn.in-berlin.de ([192.109.42.8]:45209 "EHLO einhorn.in-berlin.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932869Ab1JaMWP (ORCPT ); Mon, 31 Oct 2011 08:22:15 -0400 In-Reply-To: Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Julian Calaby Cc: yoma sophian , linux-scsi@vger.kernel.org On Oct 31 Julian Calaby wrote: > Hi, > > On Mon, Oct 31, 2011 at 12:53, yoma sophian wrote: > > hi stefan: > > Thanks for your reply. > > 2011/10/30, Stefan Richter : > >> The low level driver, not SCSI core, is responsible to obtain a DMA > >> address. > > > > Why I ask this because I found there is no same transformation for > > scsi usb subsystem. > > Would anyone can let me know where it is? > > I am not familiar with the code in question, but I would guess that > this would happen in the USB Controller Interface driver. I don't know the USB subsystem either. Anyway, in this case the "SCSI low-level" (i.e. SCSI transport and interconnect driver) internally consists of USB high-level (storage), USB core, and USB low-level (UHCI, EHCI or whatever). "grep -r dma_map_sg drivers/usb/" shows occurrences of scatter-gather list DMA mappings in the USB core. I haven't checked whether these are indeed the ones that the usb-storage driver relies on. -- Stefan Richter -=====-==-== =-=- ===== http://arcgraph.de/sr/