drm/i915: Initialise min/max frequencies before updating RPS registers

The RPS register writing routines use the current value of min/max to
set certain limits and interrupt gating. If we set those afterwards, we
risk setting up the hw incorrectly and losing power management events,
and worse, trigger some internal assertions.

Reorder the calling sequences to be correct, and remove the then
unrequired clamping from inside set_rps(). And for a bonus, fix the bug
of calling gen6_set_rps() from Valleyview.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
CC: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 5 insertions, 14 deletions

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 38943f8ef260..e37860377285 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3414,26 +3414,19 @@ static void ironlake_disable_drps(struct drm_device *dev)
  * ourselves, instead of doing a rmw cycle (which might result in us clearing
  * all limits and the gpu stuck at whatever frequency it is at atm).
  */
-static u32 gen6_rps_limits(struct drm_i915_private *dev_priv, u8 *val)
+static u32 gen6_rps_limits(struct drm_i915_private *dev_priv, u8 val)
 {
         u32 limits;
 
-        limits = 0;
-
-        if (*val >= dev_priv->rps.max_delay)
-                *val = dev_priv->rps.max_delay;
-        limits |= dev_priv->rps.max_delay << 24;
-
         /* Only set the down limit when we've reached the lowest level to avoid
          * getting more interrupts, otherwise leave this clear. This prevents a
          * race in the hw when coming out of rc6: There's a tiny window where
          * the hw runs at the minimal clock before selecting the desired
          * frequency, if the down threshold expires in that window we will not
          * receive a down interrupt. */
-        if (*val <= dev_priv->rps.min_delay) {
-                *val = dev_priv->rps.min_delay;
+        limits = dev_priv->rps.max_delay << 24;
+        if (val <= dev_priv->rps.min_delay)
                 limits |= dev_priv->rps.min_delay << 16;
-        }
 
         return limits;
 }
@@ -3533,7 +3526,6 @@ static void gen6_set_rps_thresholds(struct drm_i915_private *dev_priv, u8 val)
 void gen6_set_rps(struct drm_device *dev, u8 val)
 {
         struct drm_i915_private *dev_priv = dev->dev_private;
-        u32 limits = gen6_rps_limits(dev_priv, &val);
 
         WARN_ON(!mutex_is_locked(&dev_priv->rps.hw_lock));
         WARN_ON(val > dev_priv->rps.max_delay);
@@ -3556,7 +3548,8 @@ void gen6_set_rps(struct drm_device *dev, u8 val)
         /* Make sure we continue to get interrupts
          * until we hit the minimum or maximum frequencies.
          */
-        I915_WRITE(GEN6_RP_INTERRUPT_LIMITS, limits);
+        I915_WRITE(GEN6_RP_INTERRUPT_LIMITS,
+                   gen6_rps_limits(dev_priv, val));
 
         POSTING_READ(GEN6_RPNSWREQ);
 
@@ -3620,8 +3613,6 @@ void valleyview_set_rps(struct drm_device *dev, u8 val)
 {
         struct drm_i915_private *dev_priv = dev->dev_private;
 
-        gen6_rps_limits(dev_priv, &val);
-
         WARN_ON(!mutex_is_locked(&dev_priv->rps.hw_lock));
         WARN_ON(val > dev_priv->rps.max_delay);
         WARN_ON(val < dev_priv->rps.min_delay);