We learned that the ECOBUS register was inside the GT power well, and so *did* need force wake to be read, so it gets removed from the list of 'doesn't need force wake' registers.
That means the code reading ECOBUS after forcing the mt_force_wake function to be called needs to use I915_READ_NOTRACE; it doesn't need to do more force wake fun as it's already done it manually.
This also adds a comment explaining why the MT forcewake testing code only needs to call mt_forcewake_get/put and not disable RC6 manually -- the ECOBUS read will return 0 if the device is in RC6 and isn't using MT forcewake, causing the test to work correctly.
Signed-off-by: Keith Packard keithp@keithp.com Cc: Jesse Barnes jbarnes@virtuousgeek.org --- drivers/gpu/drm/i915/i915_drv.c | 7 ------- drivers/gpu/drm/i915/i915_drv.h | 3 +-- drivers/gpu/drm/i915/intel_display.c | 8 +++++++- 3 files changed, 8 insertions(+), 10 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c index 28836fe..e63a0f0 100644 --- a/drivers/gpu/drm/i915/i915_drv.c +++ b/drivers/gpu/drm/i915/i915_drv.c @@ -922,13 +922,6 @@ MODULE_AUTHOR(DRIVER_AUTHOR); MODULE_DESCRIPTION(DRIVER_DESC); MODULE_LICENSE("GPL and additional rights");
-/* We give fast paths for the really cool registers */ -#define NEEDS_FORCE_WAKE(dev_priv, reg) \ - (((dev_priv)->info->gen >= 6) && \ - ((reg) < 0x40000) && \ - ((reg) != FORCEWAKE) && \ - ((reg) != ECOBUS)) - #define __i915_read(x, y) \ u##x i915_read##x(struct drm_i915_private *dev_priv, u32 reg) { \ u##x val = 0; \ diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index 1421118..bbd0604 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -1364,8 +1364,7 @@ void __gen6_gt_wait_for_fifo(struct drm_i915_private *dev_priv); #define NEEDS_FORCE_WAKE(dev_priv, reg) \ (((dev_priv)->info->gen >= 6) && \ ((reg) < 0x40000) && \ - ((reg) != FORCEWAKE) && \ - ((reg) != ECOBUS)) + ((reg) != FORCEWAKE))
#define __i915_read(x, y) \ u##x i915_read##x(struct drm_i915_private *dev_priv, u32 reg); diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index a03ebf6..5abfc36 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -8539,9 +8539,15 @@ static void intel_init_display(struct drm_device *dev) if (IS_IVYBRIDGE(dev)) { u32 ecobus;
+ /* A small trick here - if the bios hasn't configured MT forcewake, + * and if the device is in RC6, then force_wake_mt_get will not wake + * the device and the ECOBUS read will return zero. Which will be + * (correctly) interpreted by the test below as MT forcewake being + * disabled. + */ mutex_lock(&dev->struct_mutex); __gen6_gt_force_wake_mt_get(dev_priv); - ecobus = I915_READ(ECOBUS); + ecobus = I915_READ_NOTRACE(ECOBUS); __gen6_gt_force_wake_mt_put(dev_priv); mutex_unlock(&dev->struct_mutex);