Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753973AbdLNSAs (ORCPT ); Thu, 14 Dec 2017 13:00:48 -0500 Received: from mail-wm0-f50.google.com ([74.125.82.50]:41129 "EHLO mail-wm0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753537AbdLNSAq (ORCPT ); Thu, 14 Dec 2017 13:00:46 -0500 X-Google-Smtp-Source: ACJfBos+SlDngYZvWwmL3rsdCUtqmqu660nr/MTzvxKedyq94hoXgz2YK8aaewRXf6Yw7k/TBLvf3A== Date: Thu, 14 Dec 2017 19:00:42 +0100 From: Krzysztof Kozlowski To: Marek Szyprowski Cc: Shuah Khan , linux@armlinux.org.uk, kgene@kernel.org, linux.amoon@gmail.com, arnd@arndb.de, javier@dowhile0.org, robie@justgohome.co.uk, shuah@kernel.org, viresh.kumar@linaro.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] ARM: exynos_defconfig - enable CONFIG_EXYNOS_IOMMU Message-ID: <20171214180042.5rbeqeocdfyt3xj7@kozik-lap> References: <20171212213110.20893-1-shuahkh@osg.samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1484 Lines: 36 On Wed, Dec 13, 2017 at 10:42:33AM +0100, Marek Szyprowski wrote: > Hi Shuah, > > On 2017-12-12 22:31, Shuah Khan wrote: > > EXYNOS_IOMMU is disabled in exynos_defconfig since it is known to cause > > boot failures on Exynos Chrome-books. The recommendation is for IOMMU to > > be enabled manually on systems as needed. > > > > A recent exynos_drm change added a warning message when EXYNOS_IOMMU is > > disabled. It is necessary to enable it to avoid the warning messages. > > A few initial tests have shown that enabling EXYNOS_IOMMU might be safe > > on Exynos Chrome-books. > > > > Enable CONFIG_EXYNOS_IOMMU in exynos_defconfig. > > > > Signed-off-by: Shuah Khan > > Due to some other changes in the order of operations during boot process, > power domains are initialized very early and because of the temporary > lack of devices (which are not yet added to the system), are turned off. > > This practically stops FIMD for scanning framebuffer very early during > boot, before IOMMU gets initialized and "solves" the issue, which was > the reason to disable Exynos IOMMU by default. > > Like I've already said, I've checked Exynos Snow Chromebook boots fine > with IOMMU support enabled, both with v4.15-rc3 and linux-next. > > Acked-by: Marek Szyprowski > Tested-by: Marek Szyprowski Thanks, applied with rephrased and extended message using Marek's explanation. Best regards, Krzysztof