From mboxrd@z Thu Jan 1 00:00:00 1970 From: Catalin Marinas Subject: Re: [PATCH v7 00/17] Introduce ACPI for ARM64 based on ACPI 5.1 Date: Fri, 16 Jan 2015 15:25:41 +0000 Message-ID: <20150116152541.GG13634@e104818-lin.cambridge.arm.com> References: <1421247905-3749-1-git-send-email-hanjun.guo@linaro.org> <54B9240A.7060003@amd.com> <20150116145545.GR7091@arm.com> <2198633.UpIyI82Yon@wuerfel> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from foss-mx-na.foss.arm.com ([217.140.108.86]:36197 "EHLO foss-mx-na.foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753408AbbAPPZz (ORCPT ); Fri, 16 Jan 2015 10:25:55 -0500 Content-Disposition: inline In-Reply-To: <2198633.UpIyI82Yon@wuerfel> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Arnd Bergmann Cc: "linux-arm-kernel@lists.infradead.org" , Will Deacon , Tom Lendacky , Mark Rutland , linaro-acpi , Yijing Wang , Rob Herring , Lorenzo Pieralisi , Timur Tabi , ACPI Devel Mailing List , "grant.likely@linaro.org" , Charles Garcia-Tobin , "phoenix.liyi@huawei.com" , Robert Richter , Jason Cooper , Marc Zyngier , "jcm@redhat.com" , Mark Brown , Bjorn Helgaas , "graeme.gregory@linaro.org" , Randy On Fri, Jan 16, 2015 at 03:14:13PM +0000, Arnd Bergmann wrote: > On Friday 16 January 2015 14:55:45 Will Deacon wrote: > > On Fri, Jan 16, 2015 at 02:45:30PM +0000, Tom Lendacky wrote: > > > I have tested ACPI-enablement patches for the amd-xgbe/amd-xgbe-phy > > > drivers that I'm about to submit upstream with the V7 patch series > > > on the AMD Seattle server platform. There does not appear to be support > > > for the _CCA attribute in this patch series. The amd-xgbe driver will > > > setup the device domain and cache attributes based on the presence of > > > this attribute, but it requires the arch support to assign the proper > > > DMA operations in order for it to all work correctly. > > > > > > Overriding the _CCA attribute in the driver, I was able to successfully > > > test the driver and this patch series. > > > > Hopefully this will all be addressed when the IORT parts of ACPI have > > settled down (the current proposal allows for these attributes to be > > described as well as their interaction with things like IOMMUs). > > > > In the meantime, are you falling back to non-coherent DMA? If so, what > > attributes have you settled on? We need to be really careful not to > > corrupt data during cache invalidatation when mapping a non-coherent > > buffer for the CPU. > > I think in case of ACPI we should use cache-coherent as the default, > as this is what all servers will use for DMA masters. Last time I heard in some call, it was agreed that _CCA properties should always be present and Linux should not make any assumption (there is no safe assumption here). While better options may appear in ACPI, _CCA is what we currently have. -- Catalin