From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sergei Shtylyov Subject: Re: htpt366 PCI latency value is really high Date: Thu, 26 Apr 2007 18:30:33 +0400 Message-ID: <4630B789.3040402@ru.mvista.com> References: <20070426064927.13d0ed72@reforged> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from h155.mvista.com ([63.81.120.155]:25673 "EHLO imap.sh.mvista.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1031055AbXDZO26 (ORCPT ); Thu, 26 Apr 2007 10:28:58 -0400 In-Reply-To: <20070426064927.13d0ed72@reforged> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Mike Mattie Cc: linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org Hello. Mike Mattie wrote: > while hunting down some latency problems I found something quite odd. > The latency reported by lspci -v for the HTP203N card is enormous. > 00:09.0 RAID bus controller: Triones Technologies, Inc. HPT302/302N > (rev 02) Subsystem: Triones Technologies, Inc. Unknown device 0001 > Flags: bus master, 66MHz, medium devsel, latency 120, IRQ 17 > I/O ports at ec00 [size=8] > I/O ports at e800 [size=4] > I/O ports at e400 [size=8] > I/O ports at e000 [size=4] > I/O ports at dc00 [size=256] > Expansion ROM at dffe0000 [disabled by cmd] [size=128K] > Capabilities: [60] Power Management version 2 > I am assuming that the "latency" field here is the PCI latency timer > which means this card is a bus hog. > From some reading on this issue linux methodically sets a sane value for > all the PCI cards it sets up, which looks normal on the rest of the system, > which is set to the value: 32 Hm, I'm only seeing clamping to the smallest of 64 and pcibios_max_latency (255) in arch/i386/pci/i386.c if the latency value is too low... Which arch are you using? > setting the value 32 with: > setpci -v -s "00:09.0" latency_timer=32 > 00:09.0 RAID bus controller: Triones Technologies, Inc. HPT302/302N (rev 02) > Subsystem: Triones Technologies, Inc. Unknown device 0001 > Flags: bus master, 66MHz, medium devsel, latency 48, IRQ 17 > I/O ports at ec00 [size=8] > I/O ports at e800 [size=4] > I/O ports at e400 [size=8] > I/O ports at e000 [size=4] > I/O ports at dc00 [size=256] > Expansion ROM at dffe0000 [disabled by cmd] [size=128K] > Capabilities: [60] Power Management version 2 > Results in 48, which is not what I asked, but hopefully this is > linux doing the right thing. Not sure -- seems likely that it's the chip's own enforced minimum instead... > I know this chipset is pretty brain-damaged, but is this > high latency value a work-around for broken hardware, or More like it. Although HighPoint's own drivers force 64. > just a oversight ? Not likely since the value is too "special"... > Cheers, > Mike Mattie - codermattie@gmail.com WBR, Sergei