[Intel-gfx] [PATCH v2] drm/i915: Don't check power domains state in intel_power_domains_init_hw()

[Chris Wilson]

Quoting Imre Deak (2018-08-28 13:22:31)
> During power domains initialization we acquire power well references for
> power wells in the INIT power domain. The rest of power wells - which
> BIOS could have left enabled - we can only acquire references as needed
> during display HW readout and so must defer sanitization until then
> (also implying that we must always do HW readout to cleanup unused power
> wells).
> 
> Thus during initialization these latter power wells can have a refcount
> of 0 while still being enabled. To avoid the false-positive state
> mismatch error this causes remove the check from
> intel_power_domains_init_hw() and rely on the state check in
> intel_power_domains_enable() which follows the HW readout.
> 
> v2:
> - Add comment to log and code clarifying how unused power wells get
>   disabled. (Chris)
> 
> Fixes: 6dfc4a8f134f ("drm/i915: Verify power domains after enabling them")
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> References: https://bugs.freedesktop.org/show_bug.cgi?id=107411
> Signed-off-by: Imre Deak <imre.deak at intel.com>

That's enough to allow me to keep following along,
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris