Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755483AbdC2JmN (ORCPT ); Wed, 29 Mar 2017 05:42:13 -0400 Received: from mx2.suse.de ([195.135.220.15]:54147 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755038AbdC2Jl5 (ORCPT ); Wed, 29 Mar 2017 05:41:57 -0400 Date: Wed, 29 Mar 2017 11:42:18 +0200 From: "'Joerg Roedel'" To: "Nath, Arindam" Cc: "Deucher, Alexander" , "'Joerg Roedel'" , Bjorn Helgaas , "linux-pci@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Daniel Drake Subject: Re: [PATCH] PCI: Blacklist AMD Stoney GPU devices for ATS Message-ID: <20170329094218.GU8329@suse.de> References: <1490703404-4944-1-git-send-email-joro@8bytes.org> <20170328202844.GQ8329@suse.de> <20170328205616.GR8329@suse.de> <20170328222627.GS8329@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 801 Lines: 21 Hi Arindam, On Wed, Mar 29, 2017 at 07:15:42AM +0000, Nath, Arindam wrote: > Joerg, as per my limited understanding of ATS, the ATC will respond to > invalidation requests after making sure there are no in-flight DMA > transactions with the address requested by IOMMU to be invalidated. > Now since the IOMMU was sending invalidate command to GPU even though > there was no explicit page unmapping request from the graphics > subsystem, we _might_ end up in a situation where the ATC takes longer > than the invalidation timeout to respond to IOMMU. The maximum wait-time in the loop is 100ms. This should be more than enough for the ATC to complete any in-flight transaction and flush its internal TLB. If that is not enough, there is almost certainly something wrong with the hardware. Joerg