[Intel-gfx] [PATCH 1/1] drm/i915: allow to select rc6 modes via kernel parameter

[Chris Wilson]

On Sat, 11 Feb 2012 17:23:32 -0200, Eugeni Dodonov <eugeni.dodonov at intel.com> wrote:
> This allows to select which rc6 modes are to be used via kernel parameter,
> via a bitmask parameter. E.g.:
> 
> - to enable rc6, i915_enable_rc6=1
> - to enable rc6 and deep rc6, i915_enable_rc6=3
> - to enable rc6 and deepest rc6, use i915_enable_rc6=5
> - to enable rc6, deep and deepest rc6, use i915_enable_rc6=7
> 
> Please keep in mind that the deepest RC6 state really should NOT be used
> by default, as it could potentially worsen the issues with deep RC6. So do
> enable it only when you know what you are doing. However, having it around
> could help solving possible future rc6-related issues and their debugging
> on user machines.
> 
> Note that this changes behavior - previously, value of 1 would enable both
> RC6 and deep RC6. Now it should only enable RC6 and deep/deepest RC6
> stages must be enabled manually.
> 
> v2: address Chris Wilson comments and clean up the code.

Wow, that comment is superb! Definitely a standard we should try to
achieve everywhere.

> Signed-off-by: Eugeni Dodonov <eugeni.dodonov at intel.com>
References: https://bugs.freedesktop.org/show_bug.cgi?id=42579
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre