[Intel-gfx] [PATCH 06/16] drm/i915: Don't call modeset related functions when display is disabled

[Jani Nikula]

On Mon, 22 Oct 2018, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> Quoting Jani Nikula (2018-10-22 09:25:45)
>> On Fri, 12 Oct 2018, José Roberto de Souza <jose.souza at intel.com> wrote:
>> > Display features should not be initialized or deinitialized when
>> > display is disabled.
>
> I completely disagree with this assertion. If the display is disabled,
> so must all the associated hw so that we can power down the entire
> chipset when idle. That means we have to complete the probe (so we
> continue to rely on fuses and in place of accurate fuses pci-id quirks
> for the infamous chipsets) and switch it off.

That actually doesn't contradict with what I said about
HAS_DISPLAY(). In many cases I think the early return on no display is
the right thing to do. However, no display isn't the same as display
disabled by module parameter (or whatnot)... which does require probe
before disable to achieve the power down.

But is the power down on display disable by module parameter a
requirement for us?

BR,
Jani.


-- 
Jani Nikula, Intel Open Source Graphics Center