[Intel-gfx] [PATCH] drm/i915: only disable default vga device

[Emil Velikov]

Hi Ville,

On Mon, 17 May 2021 at 18:24, Ville Syrjälä
<ville.syrjala at linux.intel.com> wrote:
>
> On Sun, May 16, 2021 at 06:14:32PM +0100, Emil Velikov wrote:
> > From: Vivek Das Mohapatra <vivek at collabora.com>
> >
> > This patch is to do with seamless handover, eg when the sequence is
> > bootloader → plymouth → desktop.
> >
> > It switches the vga arbiter from the "other" GPU to the default one
> > (intel in this case), so the driver can issue some io().
>
> I don't understand what this commit message is trying to say.
>
Bunch of context is lost due to the patch age, so I'm not 100% sure of
the actual hardware setup where this occurs.
Does the following make sense?

Currently on dual GPU systems, we do not get seamless handover as the
output flickers during the transition bootloader -> plymouth ->
desktop.
This happens as a result of switching (via the VGA arbiter) from the
"other" GPU back to the default i915 one and issuing io() commands.

-Emil