[Intel-gfx] [RFC] drm/i915: support zero flicker boot

[Jesse Barnes]

On Thu, 22 Oct 2009 16:45:49 +0900
"H. Peter Anvin" <hpa at zytor.com> wrote:

> On 10/22/2009 03:42 PM, Jesse Barnes wrote:
> > If the BIOS programs the native panel mode at boot and the boot
> > loader leaves it alone, we should be able to boot with zero
> > flicker.  This patch fixes up the "mode_switch" test in
> > drm_crtc_helper's set_config function and adds code to the i915
> > display init function to set the current CRTC mode and enable
> > flag.  If the eventual mode programmed matches the current mode, we
> > should have no need to turn the display off and then on again.
> >
> > Any thoughts?  Peter you may already have a similar bit of code for
> > the testing you've been doing?
> >
> > Jesse
> 
> I haven't, no, but when I get back to the U.S. I will test it with
> the native-video-mode bootloader I have.
> 
> Unfortunately I don't have that machine with me.

Oh and drm_modes_equal needs fixing to prevent it failing if just
DRM_MODE_PREFERRED is different and everything else is equal.  We
should probably split flags for that between actual mode information
and metadata like preferred.

Jesse