14.04.2020 22:32, dbasehore . пишет: > Hi Dmitry, sorry for the late reply. > > On Sun, Mar 8, 2020 at 12:25 PM Dmitry Osipenko <digetx@xxxxxxxxx> wrote: >> >> 06.03.2020 03:21, Derek Basehore пишет: >>> This adds the plumbing for reading panel rotation from the devicetree >>> and sets up adding a panel property for the panel orientation on >>> Mediatek SoCs when a rotation is present. >> >> Hello Derek and everyone, >> >> I'm looking at adding display rotation support to NVIDIA Tegra DRM >> driver because some devices have display panel physically mounted >> upside-down, and thus, display controller's scan-out needs to be rotated >> by 180° in this case. >> >> Derek, yours panel-rotation patches add support for assigning panel's >> orientation to the connector, but then only primary display plane >> receives rotation value in [1], while rotation needs to be applied to >> all available overlay/cursor planes and this should happen in other >> places than [1] as well. > > This is intended. We don't correct the output in the kernel. We > instead rely on notifying userspace that the panel is rotated, then we > handle it there. > >> >> [1] drm_client_modeset_commit_atomic() >> >> Please also note that in a case of the scan-out rotation, plane's >> coordinates need to be changed in accordance to the display's rotation. >> >> I looked briefly through the DRM code and my understanding that the DRM >> core currently doesn't support use-case where scan-out needs to rotated >> based on a panel's orientation, correct? Is it the use-case you're >> working on for the Mediatek driver? > > Yes, we rely on userspace to rotate the output. The major reason for > this is because there may not be a "free" hardware rotation that can > be applied to the overlay. Sean Paul and others also preferred that > userspace control what is output to the screen instead of the kernel > taking care of it. This code just adds the drm property to the panel. > Could you please explain what that userspace is? AFAIK, things like Xorg modesetting don't support that orientation property.
