Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751817AbZIIGqG (ORCPT ); Wed, 9 Sep 2009 02:46:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751353AbZIIGqF (ORCPT ); Wed, 9 Sep 2009 02:46:05 -0400 Received: from idcmail-mo1so.shaw.ca ([24.71.223.10]:7243 "EHLO idcmail-mo1so.shaw.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751365AbZIIGqE (ORCPT ); Wed, 9 Sep 2009 02:46:04 -0400 X-Cloudmark-SP-Filtered: true X-Cloudmark-SP-Result: v=1.0 c=1 a=eKIDt7sAMm0A:10 a=w4iE+TBsmj5y1WloLYF40w==:17 a=VwQbUJbxAAAA:8 a=W0vUJOdyAAAA:8 a=7VSSB5tv1T7x5RZTjvkA:9 a=34KhdaRnWScWSk1R6ZwA:7 a=atiuE7bvpy_Wmov4X6XkNTq3w2wA:4 a=x8gzFH9gYPwA:10 From: Thomas Fjellstrom Reply-To: tfjellstrom@shaw.ca To: linux-kernel@vger.kernel.org Subject: Re: Limiting DMA speeds for individual IDE drives Date: Wed, 9 Sep 2009 00:46:06 -0600 User-Agent: KMail/1.12.1 (Linux/2.6.31-rc8; KDE/4.3.1; x86_64; ; ) References: In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <200909090046.06707.tfjellstrom@shaw.ca> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4203 Lines: 93 On Tue September 8 2009, Alan Stern wrote: > On Tue, 8 Sep 2009, Alan Cox wrote: > > > I've got a situation where a drive claims to be capable of supporting > > > UDMA/100, but it's in a noisy environment and gets lots of errors at > > > that speed. I'd like to limit it to UDMA/66 or even UDMA/33. > > > > That should never occur with a proper cable and I would be concerned the > > fault might be something more problematic such as speed misconfiguration > > or an incompatibility. Which driver is in use ? > > The cable indeed is likely to be at fault. The same drive worked okay > at the higher speed with a different cable (which unfortunately is > unavailable for use in the final deployment). This is using the old > IDE driver. Here's an extract from the log, with > ide-core.ignore_cable=0 specified on the command line: > I have just one suggestion. Get a new cable. > Linux version 2.6.27-gentoo-r10 (root@raise) (gcc version 4.1.2 (Gentoo > 4.1.2 p1.0.2)) #1 SMP PREEMPT Tue Apr 21 15:06:03 UTC 2009 ... > Uniform Multi-Platform E-IDE driver > piix 0000:00:1f.1: IDE controller (0x8086:0x24cb rev 0x02) > pci 0000:00:1f.1: PCI INT A -> GSI 18 (level, low) -> IRQ 18 > piix 0000:00:1f.1: IDE port disabled > piix 0000:00:1f.1: not 100% native mode: will probe irqs later > ide: ignoring cable detection for ide0 > ide0: BM-DMA at 0xf000-0xf007 > Probing IDE interface ide0... > hda: STEC MACH-8 SSD, ATA DISK drive > hda: host max PIO4 wanted PIO255(auto-tune) selected PIO4 > hda: UDMA/100 mode selected > ide0 at 0x1f0-0x1f7,0x3f6 on irq 14 > ide_generic: please use "probe_mask=0x3f" module parameter for probing all > legacy ISA IDE ports ide_generic: I/O resource 0x1F0-0x1F7 not free. > ide_generic: I/O resource 0x170-0x177 not free. > hda: max request size: 512KiB > hda: 60789456 sectors (31124 MB), CHS=16383/255/63 > hda: cache flushes not supported > hda: hda1 hda2 hda3 > ... > hda: dma_intr: status=0x51 { DriveReady SeekComplete Error } > hda: dma_intr: error=0xc4 { DriveStatusError BadCRC UncorrectableError }, > LBAsect=14823116, sector=14823116 ide: failed opcode was: unknown > hda: dma_intr: status=0x51 { DriveReady SeekComplete Error } > hda: dma_intr: error=0xc4 { DriveStatusError BadCRC UncorrectableError }, > LBAsect=15133492, sector=15133492 ide: failed opcode was: unknown > hda: dma_intr: status=0x51 { DriveReady SeekComplete Error } > hda: dma_intr: error=0xc4 { DriveStatusError BadCRC UncorrectableError }, > LBAsect=9478100, sector=9478100 ide: failed opcode was: unknown > Etc.; you get the idea... > > > > The hdparm command should be able to do this but I can't run it until > > > the system has booted, by which time a bunch of CRC and possibly other > > > errors have already occurred. Ideally it should be possible to limit > > > > Only the data transfers are CRC protected and at high speed, but noise at > > low speed would be a real concern as the commands are sent low speed but > > without protection on PATA devices - so a bit flip can send a DMA to the > > wrong sector. > > > > > the speed starting as early as device detection, but I can't find any > > > way to do it. Is there support for such a thing or will I have to hack > > > it in? > > > > You can disallow DMA but not clip DMA to UDMA33 with the old driver. You > > could disallow DMA at boot and reallow it with a speed set by hdparm in > > your boot scripts... > > On Tue, 8 Sep 2009, Frederik Deweerdt wrote: > > Does passing ide=nodma at bootime, and then having init set the DMA at > > the right speed, would work? > > I'll recommend trying that out. Thanks to both of you for the advice. > > 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/ > -- Thomas Fjellstrom tfjellstrom@shaw.ca -- 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/