[Intel-gfx] [PATCH] drm/i915: Hold runtime PM during plane commit

[Matt Roper]

During plane operations, we read/write some registers that only operate
properly if we're not runtime suspended.  At the moment we're not
holding the runtime PM reference across the whole plane operation, so
there's a potential for problems.

This issue was already partially addressed by commit

        commit d6dd6843ff4a57c662dbc378b9f99a9c034b0956
        Author: Paulo Zanoni <paulo.r.zanoni at intel.com>
        Date:   Fri Aug 15 15:59:32 2014 -0300

            drm/i915: fix plane/cursor handling when runtime suspended

which took care of holding the runtime PM reference during the pin and
fence operations for plane updates.  However there are still a few
actual plane registers that we also need to hold the runtime PM
reference for.  Recent refactoring patches in preparation for atomic
have rearranged the code and made it increasingly likely that the
hardware will have time to suspend between the pin/fence operation and
the actual register writes.

The solution here grabs the runtime PM reference around the 'commit'
operation for planes, which should cover all the relevant register
reads/writes.

Cc: Paulo Zanoni <paulo.r.zanoni at intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=87180
Signed-off-by: Matt Roper <matthew.d.roper at intel.com>
---
 drivers/gpu/drm/i915/intel_display.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 3044af5..a0ddce5 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -11863,6 +11863,7 @@ intel_update_plane(struct drm_plane *plane, struct drm_crtc *crtc,
 		   uint32_t src_w, uint32_t src_h)
 {
 	struct drm_device *dev = plane->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct drm_framebuffer *old_fb = plane->fb;
 	struct intel_plane_state state;
 	struct intel_plane *intel_plane = to_intel_plane(plane);
@@ -11902,7 +11903,9 @@ intel_update_plane(struct drm_plane *plane, struct drm_crtc *crtc,
 			return ret;
 	}
 
+	intel_runtime_pm_get(dev_priv);
 	intel_plane->commit_plane(plane, &state);
+	intel_runtime_pm_put(dev_priv);
 
 	if (fb != old_fb && old_fb) {
 		if (intel_crtc->active)
-- 
1.8.5.1