From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kevin Hilman Subject: Re: [PATCH 1/1] Revert "ARM: dts: add display power domain for exynos5250" Date: Wed, 29 Apr 2015 10:40:07 -0700 Message-ID: <7hr3r2suiw.fsf@deeprootsystems.com> References: <1427107800-21668-1-git-send-email-javier.martinez@collabora.co.uk> Mime-Version: 1.0 Content-Type: text/plain Return-path: In-Reply-To: <1427107800-21668-1-git-send-email-javier.martinez@collabora.co.uk> (Javier Martinez Canillas's message of "Mon, 23 Mar 2015 11:49:59 +0100") Sender: linux-kernel-owner@vger.kernel.org To: Javier Martinez Canillas Cc: Kukjin Kim , Olof Johansson , Andreas =?utf-8?Q?F=C3=A4rber?= , Marek Szyprowski , Doug Anderson , Andrzej Hajda , linux-samsung-soc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, inki.dae@samsung.com List-Id: linux-samsung-soc@vger.kernel.org Javier Martinez Canillas writes: > This reverts commit 2d2c9a8d0a4f90e298315d2f4a282d8bd5d45e5c > ("ARM: dts: add display power domain for exynos5250"). > > The mentioned commit added a domain definition for the DISP1 > power domain and references to it in the appropriate devices > but this change breaks the display in at least the Exynos5250 > based Snow and Spring Chromebooks. > > On these machines, the boot-loader enables the DISP1 domain and > before the mentioned commit, the kernel didn't know about it so > the power domain remained always enabled. > > But after that commit when the exynos-dp probe is deferred, > the DISP1 domain is powered off and on again but the exynos-dp > driver fails to configure the video showing the following error: > > exynos-dp 145b0000.dp-controller: Timeout of video streamclk ok > exynos-dp 145b0000.dp-controller: unable to config video > > The same issue happens when the display is turned off and on > again using DPMS. > > So, it seems the DISP1 power domain definition is not complete > since the display works with the initialization made by the boot > loader but it does not work when the power domain is enabled by > the kernel. > > Having the definition in the DTS makes the power domain to be > powered on when needed and powered off when not needed which is > better in terms of power consumption but for now is safer to just > revert the commit to avoid adding a regression in some machines. > > Signed-off-by: Javier Martinez Canillas Tested-by: Kevin Hilman FWIW, this patch fixes the boot panics when using MMC rootfs on exynos5800-peach-pi with current linux-next that have been happening for awhile. For several months now, DRM/display related stuff is very routinely breaking basic booting on exynos5, which gives the rather strong impression that the DRM stuff is not tested well enough to be merged. Kevin