[PATCH] drm/i915: fix plane/cursor handling when runtime suspended

[Paulo Zanoni <przanoni@gmail.com>]

From: Paulo Zanoni <paulo.r.zanoni@intel.com>

If we're runtime suspended and try to use the plane interfaces, we
will get a lot of WARNs saying we did the wrong thing.

We need to get runtime PM references to pin/unpin the objects, and to
change the fences. The pin/unpin functions are the ideal places for
this, but intel_crtc_cursor_set_obj() doesn't call them, so we also
have to add get/put calls inside it. There is no problem if we runtime
suspend right after these functions are finished, because the
registers written are forwarded to system memory.

Note: for a complete fix of the cursor-dpms test case, we also need
the patch named "drm/i915: Don't try to enable cursor from setplane
when crtc is disabled".

v2: - Narrow the put/get calls on intel_crtc_cursor_set_obj() (Daniel)
v3: - Make get/put also surround the fence and unpin calls (Daniel and
      Ville).
    - Merge all the plane changes into a single patch since they're
      the same fix.
    - Add the comment requested by Daniel.
v4: - Remove spurious whitespace (Ville).
v5: - Remove intel_crtc_update_cursor() chunk since Ville did an
      equivalent fix in another patch (Ville).

Testcase: igt/pm_rpm/cursor
Testcase: igt/pm_rpm/cursor-dpms
Testcase: igt/pm_rpm/legacy-planes
Testcase: igt/pm_rpm/legacy-planes-dpms
Testcase: igt/pm_rpm/universal-planes
Testcase: igt/pm_rpm/universal-planes-dpms
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=81645
Cc: stable@vger.kernel.org
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
---
 drivers/gpu/drm/i915/intel_display.c | 35 ++++++++++++++++++++++++++++++++++-
 1 file changed, 34 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index a1cf052..2db9e06 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2149,6 +2149,15 @@ intel_pin_and_fence_fb_obj(struct drm_device *dev,
 	if (need_vtd_wa(dev) && alignment < 256 * 1024)
 		alignment = 256 * 1024;
 
+	/*
+	 * Global gtt pte registers are special registers which actually forward
+	 * writes to a chunk of system memory. Which means that there is no risk
+	 * that the register values disappear as soon as we call
+	 * intel_runtime_pm_put(), so it is correct to wrap only the
+	 * pin/unpin/fence and not more.
+	 */
+	intel_runtime_pm_get(dev_priv);
+
 	dev_priv->mm.interruptible = false;
 	ret = i915_gem_object_pin_to_display_plane(obj, alignment, pipelined);
 	if (ret)
@@ -2166,21 +2175,30 @@ intel_pin_and_fence_fb_obj(struct drm_device *dev,
 	i915_gem_object_pin_fence(obj);
 
 	dev_priv->mm.interruptible = true;
+	intel_runtime_pm_put(dev_priv);
 	return 0;
 
 err_unpin:
 	i915_gem_object_unpin_from_display_plane(obj);
 err_interruptible:
 	dev_priv->mm.interruptible = true;
+	intel_runtime_pm_put(dev_priv);
 	return ret;
 }
 
 void intel_unpin_fb_obj(struct drm_i915_gem_object *obj)
 {
-	WARN_ON(!mutex_is_locked(&obj->base.dev->struct_mutex));
+	struct drm_device *dev = obj->base.dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+
+	WARN_ON(!mutex_is_locked(&dev->struct_mutex));
+
+	intel_runtime_pm_get(dev_priv);
 
 	i915_gem_object_unpin_fence(obj);
 	i915_gem_object_unpin_from_display_plane(obj);
+
+	intel_runtime_pm_put(dev_priv);
 }
 
 /* Computes the linear offset to the base tile and adjusts x, y. bytes per pixel
@@ -8170,6 +8188,16 @@ static int intel_crtc_cursor_set_obj(struct drm_crtc *crtc,
 
 	/* we only need to pin inside GTT if cursor is non-phy */
 	mutex_lock(&dev->struct_mutex);
+
+	/*
+	 * Global gtt pte registers are special registers which actually forward
+	 * writes to a chunk of system memory. Which means that there is no risk
+	 * that the register values disappear as soon as we call
+	 * intel_runtime_pm_put(), so it is correct to wrap only the
+	 * pin/unpin/fence and not more.
+	 */
+	intel_runtime_pm_get(dev_priv);
+
 	if (!INTEL_INFO(dev)->cursor_needs_physical) {
 		unsigned alignment;
 
@@ -8219,6 +8247,10 @@ static int intel_crtc_cursor_set_obj(struct drm_crtc *crtc,
 
 	i915_gem_track_fb(intel_crtc->cursor_bo, obj,
 			  INTEL_FRONTBUFFER_CURSOR(pipe));
+
+	if (obj)
+		intel_runtime_pm_put(dev_priv);
+
 	mutex_unlock(&dev->struct_mutex);
 
 	old_width = intel_crtc->cursor_width;
@@ -8240,6 +8272,7 @@ static int intel_crtc_cursor_set_obj(struct drm_crtc *crtc,
 fail_unpin:
 	i915_gem_object_unpin_from_display_plane(obj);
 fail_locked:
+	intel_runtime_pm_put(dev_priv);
 	mutex_unlock(&dev->struct_mutex);
 fail:
 	drm_gem_object_unreference_unlocked(&obj->base);
-- 
2.0.1