From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: What's the SB600 64-bit DMA problem? Date: Wed, 24 Sep 2008 18:46:51 +0900 Message-ID: <48DA0C8B.3000406@gmail.com> References: <20080920151712.10515.qmail@science.horizon.com> <20080921001529.23400.qmail@science.horizon.com> <65a6ef750809231730h52f6bf47g23b33db1d2f4ca08@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from ti-out-0910.google.com ([209.85.142.184]:5977 "EHLO ti-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751216AbYIXJsU (ORCPT ); Wed, 24 Sep 2008 05:48:20 -0400 Received: by ti-out-0910.google.com with SMTP id b6so1302311tic.23 for ; Wed, 24 Sep 2008 02:48:18 -0700 (PDT) In-Reply-To: <65a6ef750809231730h52f6bf47g23b33db1d2f4ca08@mail.gmail.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Mark Nelson Cc: George Spelvin , grundler@google.com, linux-ide@vger.kernel.org, shane.huang@amd.com, jgarzik@redhat.com Mark Nelson wrote: > On Sun, Sep 21, 2008 at 10:15 AM, George Spelvin wrote: >> "Grant Grundler" wrote: >>> On Sat, Sep 20, 2008 at 8:17 AM, George Spelvin wrote: >>>> I just got a couple of MSI KA92 (AMD 790FX-based) motherboards with >>>> 8 GiB of RAM each. I noticed on boot that the SB600 AHCI implementation >>>> had a 32-bit DMA limitation, and looking in the archives, it >>>> appears that folks from AMD think it doesn't need to be there. >>> URL? >>> Just want to be sure I'm looking at the same thread. >> "About forcing 32bit DMA patch for AMD690G(SB600)" >> http://marc.info/?t=120107450600001 > > It looks like the results from people testing it further never arrived... > >>>From git commit a878539ef994787c447a98c2e3ba0fe3dad984ec ("ahci: > work around ATI SB600 h/w quirk"), it looks like the initial > idea was to limit each command to a maximum of 255 sectors (but > to still allow 64bit DMA), but according to a later commit > (4cde32fc4b32e96a99063af3183acdfd54c563f0; "ahci: SB600 > workaround is suspect... play it safe for now") this did not > solve the lockups. But there are references in the thread above > to broken MSI on the SB600 possibly being the cause of the problem, > and now that commit 22b5e7a74280deae560c20ee1a9b502b35181327 > ("ahci: SB600 ahci can't do MSI, blacklist that capability") has gone in > maybe this is why you're able to get 64bit DMA working? (although > we do need more hints on how to conclusively test this) Hmm... I doubt MSI has anything to do with 64bit DMA but then again anything is possible. Shane, anything came out of the testing? Thanks. -- tejun