Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933667Ab0BQJu0 (ORCPT ); Wed, 17 Feb 2010 04:50:26 -0500 Received: from metis.ext.pengutronix.de ([92.198.50.35]:33128 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933067Ab0BQJuY (ORCPT ); Wed, 17 Feb 2010 04:50:24 -0500 Date: Wed, 17 Feb 2010 10:50:00 +0100 From: Sascha Hauer To: Andy Green Cc: Catalin Marinas , Matthew Dharm , Sergei Shtylyov , Ming Lei , Sebastian Siewior , linux-usb@vger.kernel.org, linux-kernel , Pavel Machek , Greg KH , linux-arm-kernel Subject: Re: USB mass storage and ARM cache coherency Message-ID: <20100217095000.GA17643@pengutronix.de> References: <20100208065519.GE1290@ucw.cz> <1265622676.4020.19.camel@pc1117.cambridge.arm.com> <4B6FE162.6000004@warmcat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4B6FE162.6000004@warmcat.com> X-Sent-From: Pengutronix Entwicklungszentrum Nord - Hildesheim X-URL: http://www.pengutronix.de/ X-IRC: #ptxdist @freenode X-Accept-Language: de,en X-Accept-Content-Type: text/plain X-Impressum: Pengutronix - Industrial Linux Solutions Handelsregister: Amtsgericht Hildesheim, HRA 2686 Peiner Strasse 6-8, 31137 Hildesheim, Germany Phone: +49-5121-206917-0 | Fax: +49-5121-206917-5555 Inhaber: Dipl.-Ing. Robert Schwebel X-Message-Flag: See Message Headers for Impressum X-Uptime: 10:49:13 up 127 days, 22:38, 44 users, load average: 0.03, 0.40, 0.43 User-Agent: Mutt/1.5.18 (2008-05-17) X-SA-Exim-Connect-IP: 2001:6f8:1178:2:215:17ff:fe12:23b0 X-SA-Exim-Mail-From: sha@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1261 Lines: 28 On Mon, Feb 08, 2010 at 11:03:14AM +0100, Andy Green wrote: > On 02/08/10 10:51, Somebody in the thread at some point said: > >> We could of course flush the caches every time we get a page fault but >> that's far from optimal, especially since DMA-capable drivers to do not >> pollute the D-cache and don't need this extra flushing. Note that the >> recent ARM processors have PIPT caches but separate for I and D and it's >> the PIO drivers that pollute the D-cache. > > Just noting that AFAIK iMX31 USB and MMC drivers both are PIO at the > moment, for lack of any platform DMA support of its unusual DMA engine. The EHCI module has its own DMA engine and has nothing to do with the SDMA engine. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | -- 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/