From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262467AbTJTJ0U (ORCPT ); Mon, 20 Oct 2003 05:26:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262490AbTJTJ0T (ORCPT ); Mon, 20 Oct 2003 05:26:19 -0400 Received: from mailout.zma.compaq.com ([161.114.64.103]:39172 "EHLO zmamail03.zma.compaq.com") by vger.kernel.org with ESMTP id S262467AbTJTJ0P (ORCPT ); Mon, 20 Oct 2003 05:26:15 -0400 Date: Mon, 20 Oct 2003 11:24:45 +0200 From: Torben Mathiasen To: Bartlomiej Zolnierkiewicz Cc: Tomas Szepe , Torben Mathiasen , linux-kernel@vger.kernel.org Subject: Re: [RFT][PATCH] fix ServerWorks PIO auto-tuning Message-ID: <20031020092445.GB1685@tmathiasen> References: <200310162344.09021.bzolnier@elka.pw.edu.pl> <20031018130234.GA28095@louise.pinerecords.com> <200310181745.41768.bzolnier@elka.pw.edu.pl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200310181745.41768.bzolnier@elka.pw.edu.pl> User-Agent: Mutt/1.4.1i X-OS: Linux 2.4.22 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Oct 18 2003, Bartlomiej Zolnierkiewicz wrote: > > We depend on BIOS hints for ServerWorks and BIOS is not enabling DMA. > AFAIR we can't force DMA in this case because there are broken hardware > designs, so current behavior is safe. However more research is needed... > On a Proliant, DMA may or may not be supported on different devices, and the BIOS knows about it. So by letting it hint its setup, we have a safe way of configuring the chipset. The 'biostimings' code used a similar approach (by leaving the BIOS setup timings alone), but as you also reported, was so generic that it could be dangerous for other chipsets. So if you have a Proliant where you get DMA enabled and it fails, it has to be a BIOS bug (since the BIOS hintet DMA), and I'd like to know about it. OTOH, if you have to explicitly enable DMA using hdparm, it may not be supported (since the BIOS hinted pio). BTW Tomas, that drive you're adding to your ML350G2, is that just to have a spare IDE disk drive? IIRC, the 350 is a SCSI system with only an ATAPI cdrom drive. But I could be wrong. Thanks, Torben