drm/i915: Add support for async flips in I915

Set the Async Address Update Enable bit in plane ctl
when async flip is requested.

v2: -Move the Async flip enablement to individual patch (Paulo)

v3: -Rebased.

v4: -Add separate plane hook for async flip case (Ville)

v5: -Rebased.

v6: -Move the plane hook to separate patch. (Paulo)
    -Remove the early return in skl_plane_ctl. (Paulo)

v7: -Move async address update enable to skl_plane_ctl_crtc() (Ville)

v8: -Rebased.

v9: -Rebased.

v10: -Rebased.
Signed-off-by: Karthik B S <karthik.b.s@intel.com>
Signed-off-by: Vandita Kulkarni <vandita.kulkarni@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200921110210.21182-3-karthik.b.s@intel.com

drivers/gpu/drm/i915/display/intel_display.c

@@ -4785,6 +4785,9 @@ u32 skl_plane_ctl_crtc(const struct intel_crtc_state *crtc_state)
 	struct drm_i915_private *dev_priv = to_i915(crtc_state->uapi.crtc->dev);
 	u32 plane_ctl = 0;
 
+	if (crtc_state->uapi.async_flip)
+		plane_ctl |= PLANE_CTL_ASYNC_FLIP;
+
 	if (INTEL_GEN(dev_priv) >= 10 || IS_GEMINILAKE(dev_priv))
 		return plane_ctl;
 

drivers/gpu/drm/i915/i915_reg.h

@@ -6923,6 +6923,7 @@ enum {
 #define   PLANE_CTL_TILED_X			(1 << 10)
 #define   PLANE_CTL_TILED_Y			(4 << 10)
 #define   PLANE_CTL_TILED_YF			(5 << 10)
+#define   PLANE_CTL_ASYNC_FLIP			(1 << 9)
 #define   PLANE_CTL_FLIP_HORIZONTAL		(1 << 8)
 #define   PLANE_CTL_MEDIA_DECOMPRESSION_ENABLE	(1 << 4) /* TGL+ */
 #define   PLANE_CTL_ALPHA_MASK			(0x3 << 4) /* Pre-GLK */