[Intel-gfx] [PATCH 02/20] drm/i915: Set PCH as NOP when display is disabled

[Souza, Jose]

On Thu, 2018-08-09 at 09:36 +0100, Chris Wilson wrote:
> Quoting José Roberto de Souza (2018-08-09 01:15:48)
> > num_pipes is set to 0 if disable_display is set inside
> > intel_device_info_runtime_init() but when that happen PCH will
> > already be set in intel_detect_pch().
> 
> One major thing missed is that if you disable the displays via
> modparam,
> you need to reap all the BIOS enabled displays and stolen memory that
> conflict with our usage. (We ignore the conflict so that means the
> BIOS
> can write into memory we are using elsewhere.) The same bug exists
> for
> outputs we don't recover from the BIOS, which is a regression from
> circa 3.2.

I have a working in progress patch on top of this ones that complete
power down all power wells, fixing this issue but for now you are
right.

> -Chris