Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754263Ab0BXCty (ORCPT ); Tue, 23 Feb 2010 21:49:54 -0500 Received: from gate.crashing.org ([63.228.1.57]:44044 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753260Ab0BXCtw (ORCPT ); Tue, 23 Feb 2010 21:49:52 -0500 Subject: Re: USB mass storage and ARM cache coherency From: Benjamin Herrenschmidt To: Oliver Neukum Cc: Catalin Marinas , Matthew Dharm , Russell King - ARM Linux , Greg KH , "Mankad, Maulik Ojas" , Sergei Shtylyov , Sebastian Siewior , linux-usb@vger.kernel.org, linux-kernel , James Bottomley , "Shilimkar, Santosh" , Pavel Machek , Ming Lei , linux-arm-kernel In-Reply-To: <201002192153.22159.oliver@neukum.org> References: <1266445892.16346.306.camel@pasglop> <1266599755.32546.38.camel@e102109-lin.cambridge.arm.com> <1266601011.32546.48.camel@e102109-lin.cambridge.arm.com> <201002192153.22159.oliver@neukum.org> Content-Type: text/plain; charset="UTF-8" Date: Wed, 24 Feb 2010 13:48:09 +1100 Message-ID: <1266979689.23523.1669.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: 978 Lines: 23 On Fri, 2010-02-19 at 21:53 +0100, Oliver Neukum wrote: > Am Freitag, 19. Februar 2010 18:36:51 schrieb Catalin Marinas: > > If a page is already mapped in user space, flush_dcache_page() on ARM > > does the flushing rather than deferring it to update_mmu_cache(). The > > PIO HCD drivers, however, don't call flush_dcache_page(). Is it possible > > that the HCD could transfer data into a page cache page already mapped > > in user space? My understanding is that the scenario above is possible. > > Yes, video drivers do that. In which case it would be up to the video driver to call flush_dcache_page() (though if it's v4l you are talking about, maybe it might make sense to push it into the v4l layer itself). 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/