From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Wed, 24 May 2017 10:44:50 +0200 From: Joerg Roedel To: "Deucher, Alexander" Cc: 'David Woodhouse' , 'Joerg Roedel' , Bjorn Helgaas , "linux-pci@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Daniel Drake , Samuel Sieb Subject: Re: [PATCH v2] PCI: Add ATS-disable quirk for AMD Stoney GPUs Message-ID: <20170524084450.GB12353@suse.de> References: <1491575538-22694-1-git-send-email-joro@8bytes.org> <1493893297.4904.71.camel@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-ID: Hi Alexander, On Tue, May 23, 2017 at 07:54:12PM +0000, Deucher, Alexander wrote: > I finally got an answer from the hw team and we validated ATS on > stoney as well so in theory this patch shouldn’t actually be needed. > I think we may actually be papering over some other issue. The > following patch seems to also fix this issue (and other issues): > https://www.spinics.net/lists/stable/msg172631.html Yeah, but it still looks to me like that the hardware got into some weird state with the storm of ATS invalidations sent to it. The Completion-Wait loop timeouts seen in the original bug report indicate that the IOMMU is waiting for a response that never comes. And this is probably the ATS flush completion response from the GPU, as disabling ATS on the GPU makes the issue disappear. Regards, Joerg