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 at keithp.com>
Cc: Jesse Barnes <jbarnes at 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);
--
1.7.7.3
