[PATCH] drm/tilcdc: Turn raster off in crtc reset, if it was on in the HW

[Daniel Vetter]

On Fri, May 26, 2017 at 12:56 PM, Jyri Sarha <jsarha at ti.com> wrote:
> The best possible crtc reset callback implementation would be reading
> the video mode information from the registers and generating the new
> crtc state based on that. But I have no idea what I should do with
> framebuffer that was used and how to show that in the state variable.
> Anyway, right now I do not have more time to spend with this.

You need to wrap it up into a real drm_framebuffer and store a
reference to that in the plane_state->fb pointer. Which means you also
need to read out the plane_state (or at least parts of it). A more
minimal approach would be to just read out the crtc state, and
force-disable all the planes on reset. That still gives you the
benefit of avoiding the modeset (since hopefully the
compositor/bootsplash/whatever just change the plane setup, not the
mode). But that only works with some hw, and not if your primary plane
is tied to the crtc.

Also, currently only i915 does such fastboot tricks, but I assume once
there's more drivers there's some big room for extracting helpers.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch