From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758173AbaJ3Hgl (ORCPT ); Thu, 30 Oct 2014 03:36:41 -0400 Received: from mailout1.w1.samsung.com ([210.118.77.11]:49286 "EHLO mailout1.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751626AbaJ3Hgj (ORCPT ); Thu, 30 Oct 2014 03:36:39 -0400 MIME-version: 1.0 Content-type: text/plain; charset=UTF-8 X-AuditID: cbfec7f5-b7f956d000005ed7-ea-5451ea84afea Content-transfer-encoding: 8BIT Message-id: <1414654594.5114.8.camel@AMDC1943> Subject: Re: [RFC 1/2] PM / Domains: Power on domain early during system resume From: Krzysztof Kozlowski To: Kevin Hilman Cc: "Rafael J. Wysocki" , Pavel Machek , Len Brown , Greg Kroah-Hartman , Inki Dae , Joonyoung Shim , Seung-Woo Kim , Kyungmin Park , David Airlie , Kukjin Kim , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, Andrzej Hajda , Marek Szyprowski , Bartlomiej Zolnierkiewicz Date: Thu, 30 Oct 2014 08:36:34 +0100 In-reply-to: <7hk33iahvu.fsf@deeprootsystems.com> References: <1414072090-11293-1-git-send-email-k.kozlowski@samsung.com> <1414072090-11293-2-git-send-email-k.kozlowski@samsung.com> <7hk33iahvu.fsf@deeprootsystems.com> X-Mailer: Evolution 3.10.4-0ubuntu2 X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprIIsWRmVeSWpSXmKPExsVy+t/xq7otrwJDDL5e4rK4te4cq0XvuZNM FhtnrGe1uPL1PZtF8+L1bBaT7k9gsXhx7yKLRe+Cq2wWTzc/ZrI42/SG3WLWlL1MFpseX2O1 uLxrDpvF594jjBYzzu9jslh75C67xd1TR9kszpy+xGoxY/JLNgdhj8V7XjJ5bFrVyeax/dsD Vo/9c9ewe9zvPs7ksXlJvceWq+0sHn1bVjF6rFj9nd3j8ya5AK4oLpuU1JzMstQifbsEroxF r44xFXzjqujZfYGtgfE1RxcjJ4eEgInEgoWLmSBsMYkL99azdTFycQgJLGWUODhnC1iCV0BQ 4sfkeyxdjBwczALyEkcuZYOEmQXUJSbNW8QMUf+ZUeLRlHXMEPV6EhvmngKzhQX8JT7duscI YrMJGEtsXr6EDcQWEVCV+LVyJ1gzs8BeVolf00+zgyRYgBKL500Ha+YUMJT49LePFWLDGkaJ +ztmMYJcISGgLNHY7zaBUWAWkvtmIdw3C8l9CxiZVzGKppYmFxQnpeca6RUn5haX5qXrJefn bmKEROPXHYxLj1kdYhTgYFTi4Y04FhAixJpYVlyZe4hRgoNZSYQ38XJgiBBvSmJlVWpRfnxR aU5q8SFGJg5OqQZGhl39HkIuLhdOR+38lrCjoeh2nWr8H5N7Kz9vffRhjZFjud6Lt4ueGl3w tMuzu2vo/0AoW37yWi6W2K1z31XvEap89f2O9buaUkfGkrofVuGTrxrZtkmeff1+u9OjjzUf TbXYb0mu9Dtd2i1n9lsxQXEpZ2fVlbonW5Yc/On4SfV2RKAY94X1SizFGYmGWsxFxYkADgHp /qQCAAA= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On śro, 2014-10-29 at 10:46 -0700, Kevin Hilman wrote: > Krzysztof Kozlowski writes: > > > When resuming the system the power domain has to be powered on early so > > any runtime PM aware devices could resume. > > > > This fixes following scenario reproduced on Exynos DRM: > > 1. Power domain is off before suspending the system. > > 2. System is suspended to RAM. > > 3. Resuming starts. The Exynos DRM driver resume callback is called. > > 4. The Exynos DRM driver calls drm_helper_resume_force_mode which turns > > the screen on by calling exynos_dsi_dpms with DRM_MODE_DPMS_ON. > > Dumb Q: if the device (and power domain) were off before (and during) > suspend, why are they being resumed? > > Shouldn't the resume path restore things to the same state they were > before suspend? One could expect that... but the Exynos DRM driver behaves differently (and some other drivers also). In resume method it calls drm_helper_resume_force_mode() which forces restoring mode setting configuration. Apparently setting a mode needs DPMS on: static void exynos_drm_crtc_commit(struct drm_crtc *crtc) { ... exynos_drm_crtc_dpms(crtc, DRM_MODE_DPMS_ON); ... The previous DPMS status (status during suspend) is completely ignored here. I dunno why... maybe someone from DRM could share some thoughts? Best regards, Krzysztof