Merge branch 'drm-fixes' of git://people.freedesktop.org/~airlied/linux

Pull drm fixes from Dave Airlie:
 "Most of the GPU drivers people were at XDC last week, so I didn't get
  much to send, so I let it rollover until this week.

  Also Alex was away for 3 weeks so amdgpu/radeon got a bit more stuff
  than usual in one go.

  I've been trying to figure out some 4.2 issues with i915 still (that
  are fixed in 4.3, but bisecting ends up in a merge commit).  Hopefully
  next week I or i915 people can work that out"

* 'drm-fixes' of git://people.freedesktop.org/~airlied/linux: (46 commits)
  drm: Allow also control clients to check the drm version
  drm/vmwgfx: Fix uninitialized return in vmw_kms_helper_dirty()
  drm/vmwgfx: Fix uninitialized return in vmw_cotable_unbind()
  drm/layerscape: fix handling fsl_dcu_drm_plane_index result
  drm/mgag200: Fix driver_load error handling
  drm/mgag200: Fix error handling paths in fbdev driver
  drm/qxl: only report first monitor as connected if we have no state
  drm/radeon: add quirk for MSI R7 370
  drm/amdgpu: Sprinkle drm_modeset_lock_all to appease locking checks
  drm/radeon: Sprinkle drm_modeset_lock_all to appease locking checks
  drm/amdgpu: sync ce and me with SWITCH_BUFFER(2)
  drm/amdgpu: integer overflow in amdgpu_mode_dumb_create()
  drm/amdgpu: info leak in amdgpu_gem_metadata_ioctl()
  drm/amdgpu: integer overflow in amdgpu_info_ioctl()
  drm/amdgpu: unwind properly in amdgpu_cs_parser_init()
  drm/amdgpu: Fix max_vblank_count value for current display engines
  drm/amdgpu: use kmemdup rather than duplicating its implementation
  drm/amdgpu: fix UVD suspend and resume for VI APU
  drm/amdgpu: fix the UVD suspend sequence order
  drm/amdgpu: make UVD handle checking more strict
  ...

1 files changed, 26 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 5a244ab9395b..39d73dbc1c47 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -640,6 +640,32 @@ static int __intel_get_crtc_scanline(struct intel_crtc *crtc)
 		position = __raw_i915_read32(dev_priv, PIPEDSL(pipe)) & DSL_LINEMASK_GEN3;
 
 	/*
+	 * On HSW, the DSL reg (0x70000) appears to return 0 if we
+	 * read it just before the start of vblank.  So try it again
+	 * so we don't accidentally end up spanning a vblank frame
+	 * increment, causing the pipe_update_end() code to squak at us.
+	 *
+	 * The nature of this problem means we can't simply check the ISR
+	 * bit and return the vblank start value; nor can we use the scanline
+	 * debug register in the transcoder as it appears to have the same
+	 * problem.  We may need to extend this to include other platforms,
+	 * but so far testing only shows the problem on HSW.
+	 */
+	if (IS_HASWELL(dev) && !position) {
+		int i, temp;
+
+		for (i = 0; i < 100; i++) {
+			udelay(1);
+			temp = __raw_i915_read32(dev_priv, PIPEDSL(pipe)) &
+				DSL_LINEMASK_GEN3;
+			if (temp != position) {
+				position = temp;
+				break;
+			}
+		}
+	}
+
+	/*
 	 * See update_scanline_offset() for the details on the
 	 * scanline_offset adjustment.
 	 */