[Precise][SRU][PATCH 1/1] drm/i915: Periodically sanity check power management

leann.ogasawara at canonical.com leann.ogasawara at canonical.com
Thu Mar 7 20:14:55 UTC 2013


From: Chris Wilson <chris at chris-wilson.co.uk>

BugLink: http://bugs.launchpad.net/bugs/1146425

Every time we use the device after a period of idleness, check that the
power management setup is still sane. This is to workaround a bug
whereby it seems that we begin suppressing power management interrupts,
preventing SandyBridge+ from going into turbo mode.

This patch does have a side-effect. It removes the mark-busy for just
moving the cursor - we don't want to increase the render clock just for
the sprite, though we may want to bump the display frequency. I'd argue
that we do not, and certainly don't want to take the struct_mutex here
due to the large latencies that introduces.

References: https://bugs.freedesktop.org/show_bug.cgi?id=44006
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>

(backported from commit 9104183dad6314c55344d65738cd719b909a3e0a)
Signed-off-by: Gajanan Bhat <gajanan.bhat at intel.com>
Signed-off-by: Leann Ogasawara <leann.ogasawara at canonical.com>
---
 drivers/gpu/drm/i915/i915_drv.h      |    3 +++
 drivers/gpu/drm/i915/intel_display.c |   43 ++++++++++++++++++++++++++++++++--
 2 files changed, 44 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 23086e8..54437bf 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -207,6 +207,7 @@ struct drm_i915_display_funcs {
 	int (*get_display_clock_speed)(struct drm_device *dev);
 	int (*get_fifo_size)(struct drm_device *dev, int plane);
 	void (*update_wm)(struct drm_device *dev);
+	void (*sanitize_pm)(struct drm_device *dev);
 	int (*crtc_mode_set)(struct drm_crtc *crtc,
 			     struct drm_display_mode *mode,
 			     struct drm_display_mode *adjusted_mode,
@@ -1366,6 +1367,8 @@ void gen6_gt_force_wake_get(struct drm_i915_private *dev_priv);
 void gen6_gt_force_wake_put(struct drm_i915_private *dev_priv);
 void __gen6_gt_wait_for_fifo(struct drm_i915_private *dev_priv);
 
+void intel_sanitize_pm(struct drm_device *dev);
+
 /* We give fast paths for the really cool registers */
 #define NEEDS_FORCE_WAKE(dev_priv, reg) \
 	(((dev_priv)->info->gen >= 6) && \
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 19b0d8d..1f2e837 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -6844,9 +6844,10 @@ void intel_mark_busy(struct drm_device *dev, struct drm_i915_gem_object *obj)
 	if (!drm_core_check_feature(dev, DRIVER_MODESET))
 		return;
 
-	if (!dev_priv->busy)
+	if (!dev_priv->busy) {
+		intel_sanitize_pm(dev);
 		dev_priv->busy = true;
-	else
+	} else
 		mod_timer(&dev_priv->idle_timer, jiffies +
 			  msecs_to_jiffies(GPU_IDLE_TIMEOUT));
 
@@ -8607,6 +8608,42 @@ void intel_init_clock_gating(struct drm_device *dev)
 		dev_priv->display.init_pch_clock_gating(dev);
 }
 
+static void gen6_sanitize_pm(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	u32 limits, delay, old;
+
+	gen6_gt_force_wake_get(dev_priv);
+
+	old = limits = I915_READ(GEN6_RP_INTERRUPT_LIMITS);
+	/* Make sure we continue to get interrupts
+	 * until we hit the minimum or maximum frequencies.
+	 */
+	limits &= ~(0x3f << 16 | 0x3f << 24);
+	delay = dev_priv->cur_delay;
+	if (delay < dev_priv->max_delay)
+		limits |= (dev_priv->max_delay & 0x3f) << 24;
+	if (delay > dev_priv->min_delay)
+		limits |= (dev_priv->min_delay & 0x3f) << 16;
+
+	if (old != limits) {
+		DRM_ERROR("Power management discrepancy: GEN6_RP_INTERRUPT_LIMITS expected %08x, was %08x\n",
+			limits, old);
+		I915_WRITE(GEN6_RP_INTERRUPT_LIMITS, limits);
+	}
+
+	gen6_gt_force_wake_put(dev_priv);
+}
+
+void intel_sanitize_pm(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+
+	if (dev_priv->display.sanitize_pm)
+		dev_priv->display.sanitize_pm(dev);
+}
+
+
 /* Set up chip specific display functions */
 static void intel_init_display(struct drm_device *dev)
 {
@@ -8713,6 +8750,7 @@ static void intel_init_display(struct drm_device *dev)
 			}
 			dev_priv->display.fdi_link_train = gen6_fdi_link_train;
 			dev_priv->display.init_clock_gating = gen6_init_clock_gating;
+			dev_priv->display.sanitize_pm = gen6_sanitize_pm;
 			dev_priv->display.write_eld = ironlake_write_eld;
 		} else if (IS_IVYBRIDGE(dev)) {
 			/* FIXME: detect B0+ stepping and use auto training */
@@ -8725,6 +8763,7 @@ static void intel_init_display(struct drm_device *dev)
 				dev_priv->display.update_wm = NULL;
 			}
 			dev_priv->display.init_clock_gating = ivybridge_init_clock_gating;
+			dev_priv->display.sanitize_pm = gen6_sanitize_pm;
 			dev_priv->display.write_eld = ironlake_write_eld;
 		} else
 			dev_priv->display.update_wm = NULL;
-- 
1.7.9.5





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