From mboxrd@z Thu Jan 1 00:00:00 1970 From: Russell King - ARM Linux Subject: Re: [PATCH] drm/exynos: fix vblank handling during dpms off Date: Thu, 9 Oct 2014 09:52:58 +0100 Message-ID: <20141009085258.GI5182@n2100.arm.linux.org.uk> References: <542B9A0E.7020206@samsung.com> <1412151287-12845-1-git-send-email-a.hajda@samsung.com> <542D13CC.5000304@samsung.com> <542D2E7C.1020904@samsung.com> <542D3C96.7000400@samsung.com> <54362066.9000504@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <54362066.9000504@nvidia.com> Sender: linux-samsung-soc-owner@vger.kernel.org To: Alexandre Courbot Cc: Andrzej Hajda , Inki Dae , Joonyoung Shim , Thierry Reding , linux-samsung-soc@vger.kernel.org, Daniel Vetter , Seung-Woo Kim , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Kyungmin Park , Kukjin Kim , Benjamin Gaignard , Ville =?iso-8859-1?Q?Syrj=E4l=E4?= , "linux-tegra@vger.kernel.org" List-Id: dri-devel@lists.freedesktop.org On Thu, Oct 09, 2014 at 02:43:02PM +0900, Alexandre Courbot wrote: > But there might be another issue, which is that calls to > drm_vblank_get() will return -EINVAL if invoked between drm_blank_off > and drm_blank_on. Is this really the desired behavior? Can it at least > happen? If so, how are drivers supposed to react to this situation? I've not yet seen the commit which causes this problem, but I hope that drm_wait_vblank() isn't affected by this. In current mainline, drm_vblank_get() is used inside drm_wait_vblank(), which is called as a result of userspace calling DRM_IOCTL_WAIT_VBLANK. So, what is the effect of this change on user applications making use of the vblank wait ioctl - and is that change intended? -- FTTC broadband for 0.8mile line: currently at 9.5Mbps down 400kbps up according to speedtest.net.