Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932481Ab0BPPob (ORCPT ); Tue, 16 Feb 2010 10:44:31 -0500 Received: from iolanthe.rowland.org ([192.131.102.54]:40453 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S932244Ab0BPPoa (ORCPT ); Tue, 16 Feb 2010 10:44:30 -0500 Date: Tue, 16 Feb 2010 10:44:26 -0500 (EST) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: "Shilimkar, Santosh" cc: Oliver Neukum , Russell King - ARM Linux , Catalin Marinas , Pavel Machek , Greg KH , Matthew Dharm , Sergei Shtylyov , Ming Lei , Sebastian Siewior , "linux-usb@vger.kernel.org" , linux-kernel , linux-arm-kernel , "Mankad, Maulik Ojas" Subject: RE: USB mass storage and ARM cache coherency In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 861 Lines: 20 On Tue, 16 Feb 2010, Shilimkar, Santosh wrote: > > Your original patch however kills ehci, ohci and uhci on some architectures. > Well the patch was making _ONLY_ control transfers use PIO and rest of > the transfer would still use dma. So not sure how much performance impact would > be because of that. > Another issue with that patch is there are few controllers which can't do PIO > at all and hence the patch would broke those controllers. More than "a few"! None of the EHCI, OHCI, or UHCI controllers used in Intel-compatible desktop and laptop systems can do PIO. That's what Oliver meant. Alan Stern -- 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/