From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S268587AbTGTV3F (ORCPT ); Sun, 20 Jul 2003 17:29:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S268589AbTGTV3F (ORCPT ); Sun, 20 Jul 2003 17:29:05 -0400 Received: from mithril.c-zone.net ([63.172.74.235]:27659 "EHLO mail.c-zone.net") by vger.kernel.org with ESMTP id S268587AbTGTV3C (ORCPT ); Sun, 20 Jul 2003 17:29:02 -0400 Message-ID: <3F1B0D4A.8000908@c-zone.net> Date: Sun, 20 Jul 2003 14:44:42 -0700 From: jiho@c-zone.net Organization: Kidding of Course User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.4) Gecko/20030624 X-Accept-Language: en-us, en MIME-Version: 1.0 To: linux-kernel CC: torvalds@osdl.org, akpm@osdl.org, alan@lxorguk.ukuu.org.uk, B.Zolnierkiewicz@elka.pw.edu.pl, vojtech@suse.cz Subject: [PATCH] 2.6.0-test1 - IDE driver VIA support (obscure bug) Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org (Apoligies if line-wrapping is nuts, I've been confined to Mozilla....) This patch fixes a *very* obscure bug, which only applies to VIA chipsets that support UDMA-133 mode, and which is only known to be tickled by one UDMA-66 hard drive (Maxtor 91360U4) that happens to report 80-wire cable detection opposite to the ATA standard. The bug appears in a test to see how the BIOS set up UDMA timing. This test is only reached when the drive says 80-wire *and* the chipset says 40-wire (which is only known to happen with this drive). The timing bits that are checked represent clocks T minus 2, i.e., ((N - 2) * T). But Vojtech forgot to subtract 2, and applied N = 8 rather than N = 6 in the test. Since the test masks the bits at 7, they are always less than 8, and the test always succeeds, even though the BIOS set UDMA-33. --- drivers/ide/pci/via82cxxx.c-orig Fri Jun 13 07:51:33 2003 +++ drivers/ide/pci/via82cxxx.c Sun Jul 20 11:38:42 2003 @@ -484,7 +484,7 @@ for (i = 24; i >= 0; i -= 8) if (((u >> i) & 0x10) || (((u >> i) & 0x20) && - (((u >> i) & 7) < 8))) { + (((u >> i) & 7) < 6))) { /* BIOS 80-wire bit or * UDMA w/ < 60ns/cycle */