Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754050AbZI2M31 (ORCPT ); Tue, 29 Sep 2009 08:29:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753955AbZI2M30 (ORCPT ); Tue, 29 Sep 2009 08:29:26 -0400 Received: from khc.piap.pl ([195.187.100.11]:55811 "EHLO khc.piap.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751585AbZI2M30 (ORCPT ); Tue, 29 Sep 2009 08:29:26 -0400 From: Krzysztof Halasa To: Arjan van de Ven Cc: "Lennart Baruschka" , Alan Cox , linux-kernel@vger.kernel.org Subject: Re: Disabling DMA with ICH10? References: <1254173481.4454.32.camel@goodbyte.homelinux.com> <20090928234025.6dc4e3f7@lxorguk.ukuu.org.uk> <20090929075416.77960@gmx.net> <20090929101114.1712314b@infradead.org> Date: Tue, 29 Sep 2009 14:29:27 +0200 In-Reply-To: <20090929101114.1712314b@infradead.org> (Arjan van de Ven's message of "Tue, 29 Sep 2009 10:11:14 +0200") 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: 831 Lines: 22 Arjan van de Ven writes: > a single PIO instruction will NOT be interrupted by an interrupt. > And can easily take several microseconds (remember: 8Mhz bus > emulation) Not that long, there is no emulation there (except for port #80 (hex?) and similar). Normal 33 MHz access. But it's still slow, of course - every access takes at least 4(?) bus cycles (IIRC: address, initiator ready, device selected, target ready). No bursts (at least on typical x86 hw). Of course ICH10 AHCI isn't connected with PCI 33/32 bus. Anyway: PIO = bad idea. -- Krzysztof Halasa -- 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/