drm/i915: Restore rps/rc6 on reset

A check of rps/rc6 state after i915_reset determined that the ring
MAX_IDLE registers were returned to their hardware defaults and that
the GEN6_PMIMR register was set to mask all interrupts. This change
restores those values to their pre-reset states by re-initializing
rps/rc6 in i915_reset. A full re-initialization was opted for versus
a targeted set of restore operations for simplicity and maintain-
ability. Note that the re-initialization is not done for Ironlake,
due to a past comment that it causes problems.

Also updated the rps initialization sequence to preserve existing
min/max values in the case of a re-init. We assume the values were
validated upon being set and do not do further range checking. The
debugfs interface for changing min/max was updated with range
checking to ensure this condition (already present in sysfs
interface).

v2: fix rps logging to output hw_max and hw_min, not rps.max_delay
    and rps.min_delay which don't strictly represent hardware limits.
    Add igt testcase to signed-off-by section.

Testcase: igt/pm_rps/reset
Signed-off-by: Jeff McGee <jeff.mcgee@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 41 insertions, 8 deletions

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index bc8707f9656f..2dc05c30b800 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -3223,6 +3223,7 @@ i915_max_freq_set(void *data, u64 val)
 {
 	struct drm_device *dev = data;
 	struct drm_i915_private *dev_priv = dev->dev_private;
+	u32 rp_state_cap, hw_max, hw_min;
 	int ret;
 
 	if (!(IS_GEN6(dev) || IS_GEN7(dev)))
@@ -3241,14 +3242,29 @@ i915_max_freq_set(void *data, u64 val)
 	 */
 	if (IS_VALLEYVIEW(dev)) {
 		val = vlv_freq_opcode(dev_priv, val);
-		dev_priv->rps.max_delay = val;
-		valleyview_set_rps(dev, val);
+
+		hw_max = valleyview_rps_max_freq(dev_priv);
+		hw_min = valleyview_rps_min_freq(dev_priv);
 	} else {
 		do_div(val, GT_FREQUENCY_MULTIPLIER);
-		dev_priv->rps.max_delay = val;
-		gen6_set_rps(dev, val);
+
+		rp_state_cap = I915_READ(GEN6_RP_STATE_CAP);
+		hw_max = dev_priv->rps.hw_max;
+		hw_min = (rp_state_cap >> 16) & 0xff;
+	}
+
+	if (val < hw_min || val > hw_max || val < dev_priv->rps.min_delay) {
+		mutex_unlock(&dev_priv->rps.hw_lock);
+		return -EINVAL;
 	}
 
+	dev_priv->rps.max_delay = val;
+
+	if (IS_VALLEYVIEW(dev))
+		valleyview_set_rps(dev, val);
+	else
+		gen6_set_rps(dev, val);
+
 	mutex_unlock(&dev_priv->rps.hw_lock);
 
 	return 0;
@@ -3288,6 +3304,7 @@ i915_min_freq_set(void *data, u64 val)
 {
 	struct drm_device *dev = data;
 	struct drm_i915_private *dev_priv = dev->dev_private;
+	u32 rp_state_cap, hw_max, hw_min;
 	int ret;
 
 	if (!(IS_GEN6(dev) || IS_GEN7(dev)))
@@ -3306,13 +3323,29 @@ i915_min_freq_set(void *data, u64 val)
 	 */
 	if (IS_VALLEYVIEW(dev)) {
 		val = vlv_freq_opcode(dev_priv, val);
-		dev_priv->rps.min_delay = val;
-		valleyview_set_rps(dev, val);
+
+		hw_max = valleyview_rps_max_freq(dev_priv);
+		hw_min = valleyview_rps_min_freq(dev_priv);
 	} else {
 		do_div(val, GT_FREQUENCY_MULTIPLIER);
-		dev_priv->rps.min_delay = val;
-		gen6_set_rps(dev, val);
+
+		rp_state_cap = I915_READ(GEN6_RP_STATE_CAP);
+		hw_max = dev_priv->rps.hw_max;
+		hw_min = (rp_state_cap >> 16) & 0xff;
+	}
+
+	if (val < hw_min || val > hw_max || val > dev_priv->rps.max_delay) {
+		mutex_unlock(&dev_priv->rps.hw_lock);
+		return -EINVAL;
 	}
+
+	dev_priv->rps.min_delay = val;
+
+	if (IS_VALLEYVIEW(dev))
+		valleyview_set_rps(dev, val);
+	else
+		gen6_set_rps(dev, val);
+
 	mutex_unlock(&dev_priv->rps.hw_lock);
 
 	return 0;