[igt-dev] [RFC i-g-t 1/1] i915/pm_backlight: turn on dpms before backlight fade out and fade in

[Chris Wilson]

Quoting Harish Chegondi (2019-03-14 06:41:48)
> backlight fade with suspend test turns off dpms which turns off
> the edp backlight and panel. Then it does a runtime suspend,
> system suspend and resume. After resume, it does a fade out and
> fade in of the backlight brightness. From the dmesg logs of the
> ci tests it appears that the test is setting the brightness
> even before the edp panel and backlight are turned on resuilting
> in the brightness values written and read to be different.
> Turn on the dpms which turns on the edp panel and backlight
> before backlight fade out and fade in. With this change the
> fade_with_suspend test passes.

But is it legal for the kernel to that? Is the kernel meant to restore
the previous configuration upon resume or leave it to userspace? What
about for fbcon?

If it is meant to leave it to userspace, why is the connector still even
enabled?
-Chris