Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933756Ab0BYUzV (ORCPT ); Thu, 25 Feb 2010 15:55:21 -0500 Received: from gate.crashing.org ([63.228.1.57]:33907 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933525Ab0BYUzU (ORCPT ); Thu, 25 Feb 2010 15:55:20 -0500 Subject: Re: USB mass storage and ARM cache coherency From: Benjamin Herrenschmidt To: Alan Stern Cc: Catalin Marinas , Matthew Dharm , linux-usb@vger.kernel.org, Russell King - ARM Linux , "Mankad,Maulik Ojas" , Sergei Shtylyov , Ming Lei , Sebastian Siewior , Oliver Neukum , linux-kernel , "Shilimkar,Santosh" , Pavel Machek , Greg KH , linux-arm-kernel , James Bottomley In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Date: Fri, 26 Feb 2010 07:52:58 +1100 Message-ID: <1267131178.23523.1729.camel@pasglop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 827 Lines: 21 On Wed, 2010-02-24 at 16:50 -0500, Alan Stern wrote: > The main issue here is that the same host controller will use PIO > sometimes and DMA sometimes, depending on the details of the > transfer. > The USB core didn't expect this and consequently we violated the rules > for DMA mapping. The question is: If the core is fixed so that the > rules aren't violated, will everything work correctly? As long as the only issue is that one (ie, doing PIO while dma-map'ed), then yes, I'd say things should work. If not, then there is -another- problem to be fixed :-) Cheers, Ben. -- 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/