drm/i915: Introduce vlv_invert_wm_value()

Add a small helper to do invert the vlv/chv values. Less fragile
perhaps, and let's us clearly mark all overlarge wateramarks as
disabled (by just making them all USHRT_MAX).

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1480354637-14209-8-git-send-email-ville.syrjala@linux.intel.com
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 0a3c26a..a23253c 100644 (file)
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -1053,6 +1053,14 @@ static void vlv_compute_fifo(struct intel_crtc *crtc)
        WARN_ON(fifo_left != 0);
 }
 
+static u16 vlv_invert_wm_value(u16 wm, u16 fifo_size)
+{
+       if (wm > fifo_size)
+               return USHRT_MAX;
+       else
+               return fifo_size - wm;
+}
+
 static void vlv_invert_wms(struct intel_crtc *crtc)
 {
        struct vlv_wm_state *wm_state = &crtc->wm_state;
@@ -1064,12 +1072,17 @@ static void vlv_invert_wms(struct intel_crtc *crtc)
                        INTEL_INFO(to_i915(dev))->num_pipes * 512 - 1;
                struct intel_plane *plane;
 
-               wm_state->sr[level].plane = sr_fifo_size - wm_state->sr[level].plane;
-               wm_state->sr[level].cursor = 63 - wm_state->sr[level].cursor;
+               wm_state->sr[level].plane =
+                       vlv_invert_wm_value(wm_state->sr[level].plane,
+                                           sr_fifo_size);
+               wm_state->sr[level].cursor =
+                       vlv_invert_wm_value(wm_state->sr[level].cursor,
+                                           63);
 
                for_each_intel_plane_on_crtc(dev, crtc, plane) {
-                       wm_state->wm[level].plane[plane->id] = plane->wm.fifo_size -
-                               wm_state->wm[level].plane[plane->id];
+                       wm_state->wm[level].plane[plane->id] =
+                               vlv_invert_wm_value(wm_state->wm[level].plane[plane->id],
+                                                   plane->wm.fifo_size);
                }
        }
 }