tree 4c3b9359270a0009150719eae585acd679cc5324
parent 7dd4906586274f3945f2aeaaa5a33b451c3b4bba
author Eugeni Dodonov <eugeni.dodonov@intel.com> 1332514638 -0300
committer Daniel Vetter <daniel.vetter@ffwll.ch> 1333276070 +0200

drm/i915: allow to select rc6 modes via kernel parameter

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.

References: https://bugs.freedesktop.org/show_bug.cgi?id=42579
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Ben Widawsky <benjamin.widawsky@intel.com>
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>