drm/i915: Reorganize WM structs/unions in CRTC state

Reorganize the nested structures and unions we have for pipe watermark
data in intel_crtc_state so that platform-specific data can be added in
a more sensible manner (and save a bit of memory at the same time).

The change basically changes the organization from:

        union {
                struct intel_pipe_wm ilk;
                struct intel_pipe_wm skl;
        } optimal;

        struct intel_pipe_wm intermediate /* ILK-only */

to

        union {
                struct {
                        struct intel_pipe_wm intermediate;
                        struct intel_pipe_wm optimal;
                } ilk;

                struct {
                        struct intel_pipe_wm optimal;
                } skl;
        }

There should be no functional change here, but it will allow us to add
more platform-specific fields going forward (and more easily extend to
other platform types like VLV).

While we're at it, let's move the entire watermark substructure out to
its own structure definition to make the code slightly more readable.

Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1463061971-19638-2-git-send-email-matthew.d.roper@intel.com
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 1bb0f9a..540c651 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -2309,7 +2309,7 @@
 	int level, max_level = ilk_wm_max_level(dev), usable_level;
 	struct ilk_wm_maximums max;
 
-	pipe_wm = &cstate->wm.optimal.ilk;
+	pipe_wm = &cstate->wm.ilk.optimal;
 
 	for_each_intel_plane_on_crtc(dev, intel_crtc, intel_plane) {
 		struct intel_plane_state *ps;
@@ -2391,7 +2391,7 @@
 				       struct intel_crtc *intel_crtc,
 				       struct intel_crtc_state *newstate)
 {
-	struct intel_pipe_wm *a = &newstate->wm.intermediate;
+	struct intel_pipe_wm *a = &newstate->wm.ilk.intermediate;
 	struct intel_pipe_wm *b = &intel_crtc->wm.active.ilk;
 	int level, max_level = ilk_wm_max_level(dev);
 
@@ -2400,7 +2400,7 @@
 	 * currently active watermarks to get values that are safe both before
 	 * and after the vblank.
 	 */
-	*a = newstate->wm.optimal.ilk;
+	*a = newstate->wm.ilk.optimal;
 	a->pipe_enabled |= b->pipe_enabled;
 	a->sprites_enabled |= b->sprites_enabled;
 	a->sprites_scaled |= b->sprites_scaled;
@@ -2429,7 +2429,7 @@
 	 * If our intermediate WM are identical to the final WM, then we can
 	 * omit the post-vblank programming; only update if it's different.
 	 */
-	if (memcmp(a, &newstate->wm.optimal.ilk, sizeof(*a)) == 0)
+	if (memcmp(a, &newstate->wm.ilk.optimal, sizeof(*a)) == 0)
 		newstate->wm.need_postvbl_update = false;
 
 	return 0;
@@ -3678,7 +3678,7 @@
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct skl_wm_values *results = &dev_priv->wm.skl_results;
 	struct intel_crtc_state *cstate = to_intel_crtc_state(crtc->state);
-	struct skl_pipe_wm *pipe_wm = &cstate->wm.optimal.skl;
+	struct skl_pipe_wm *pipe_wm = &cstate->wm.skl.optimal;
 
 
 	/* Clear all dirty flags */
@@ -3757,7 +3757,7 @@
 	struct intel_crtc *intel_crtc = to_intel_crtc(cstate->base.crtc);
 
 	mutex_lock(&dev_priv->wm.wm_mutex);
-	intel_crtc->wm.active.ilk = cstate->wm.intermediate;
+	intel_crtc->wm.active.ilk = cstate->wm.ilk.intermediate;
 	ilk_program_watermarks(dev_priv);
 	mutex_unlock(&dev_priv->wm.wm_mutex);
 }
@@ -3769,7 +3769,7 @@
 
 	mutex_lock(&dev_priv->wm.wm_mutex);
 	if (cstate->wm.need_postvbl_update) {
-		intel_crtc->wm.active.ilk = cstate->wm.optimal.ilk;
+		intel_crtc->wm.active.ilk = cstate->wm.ilk.optimal;
 		ilk_program_watermarks(dev_priv);
 	}
 	mutex_unlock(&dev_priv->wm.wm_mutex);
@@ -3826,7 +3826,7 @@
 	struct skl_wm_values *hw = &dev_priv->wm.skl_hw;
 	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
 	struct intel_crtc_state *cstate = to_intel_crtc_state(crtc->state);
-	struct skl_pipe_wm *active = &cstate->wm.optimal.skl;
+	struct skl_pipe_wm *active = &cstate->wm.skl.optimal;
 	enum pipe pipe = intel_crtc->pipe;
 	int level, i, max_level;
 	uint32_t temp;
@@ -3892,7 +3892,7 @@
 	struct ilk_wm_values *hw = &dev_priv->wm.hw;
 	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
 	struct intel_crtc_state *cstate = to_intel_crtc_state(crtc->state);
-	struct intel_pipe_wm *active = &cstate->wm.optimal.ilk;
+	struct intel_pipe_wm *active = &cstate->wm.ilk.optimal;
 	enum pipe pipe = intel_crtc->pipe;
 	static const i915_reg_t wm0_pipe_reg[] = {
 		[PIPE_A] = WM0_PIPEA_ILK,