From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: Re: [PATCHv3 3/8] drm/omap: add support for manually updated displays Date: Fri, 20 Apr 2018 07:25:33 -0700 Message-ID: <20180420142533.GN5671@atomide.com> References: <20180330171822.25896-1-sebastian.reichel@collabora.co.uk> <20180330171822.25896-4-sebastian.reichel@collabora.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Daniel Stone Cc: Tomi Valkeinen , Sebastian Reichel , Sebastian Reichel , Pavel Machek , Laurent Pinchart , Rob Herring , Mark Rutland , dri-devel , devicetree@vger.kernel.org, linux-omap@vger.kernel.org, Linux Kernel Mailing List , kernel@collabora.com List-Id: devicetree@vger.kernel.org Hi, * Daniel Stone [180420 10:21]: > Hi Tomi, > > On 20 April 2018 at 08:09, Tomi Valkeinen wrote: > > It's actually not quite clear to me how manual update displays work with > > DRM... > > > > As far as I see, we have essentially two cases: 1) single buffering, > > where the userspace must set an area in the fb dirty, which then > > triggers the update, 2) multi buffering, which doesn't need fb dirty, > > but just a page flip which triggers the update. > > > > In the 2) case (which I think is the optimal case which all the modern > > apps should use), there's no need for delayed work or any work, and the > > code flow should be very similar to the auto-update model. > > Correct. There's been talk (and I think patches?) of adding a > per-plane dirty property, so userspace can as an optimisation inform > the kernel of the area changed between frames. But short of that, a > pageflip needs to trigger a full-plane update, with no dirtyfb > required. For per-plane dirty property patches, which ones do you refer to? Then for xorg, there's my second attempt on fixing the command mode rotation at [0]. Not sure if that's enough for a fix? It seems not very efficient to me and I don't really know where the the per crtc dirty flag should be stored.. I can easily test patches though with a command mode LCD and normal HDMI setup on droid 4. Regards, Tony [0] https://lists.x.org/archives/xorg-devel/2018-February/055890.html