drm/i915: Store current watermark state in dev_priv->wm

To make it easier to check what watermark updates are actually
necessary, keep copies of the relevant bits that match the current
hardware state.

Also add DDB partitioning into hsw_wm_values as that's another piece
of state we want to track.

We don't read out the hardware state on init yet, so we can't really
start using this yet, but it will be used later.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
[danvet: Paulo asked for a comment around the memcmp to say that we
depend upon zero-initializing the entire structures due to padding.
But a later patch in this series removes the memcmp again. So this is
ok as-is.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -1141,6 +1141,15 @@ struct intel_wm_level {
 	uint32_t fbc_val;
 };
 
+struct hsw_wm_values {
+	uint32_t wm_pipe[3];
+	uint32_t wm_lp[3];
+	uint32_t wm_lp_spr[3];
+	uint32_t wm_linetime[3];
+	bool enable_fbc_wm;
+	enum intel_ddb_partitioning partitioning;
+};
+
 /*
  * This struct tracks the state needed for the Package C8+ feature.
  *
@@ -1402,6 +1411,9 @@ typedef struct drm_i915_private {
 		uint16_t spr_latency[5];
 		/* cursor */
 		uint16_t cur_latency[5];
+
+		/* current hardware state */
+		struct hsw_wm_values hw;
 	} wm;
 
 	struct i915_package_c8 pc8;

drivers/gpu/drm/i915/intel_pm.c

@@ -2200,14 +2200,6 @@ struct hsw_wm_maximums {
 	uint16_t fbc;
 };
 
-struct hsw_wm_values {
-	uint32_t wm_pipe[3];
-	uint32_t wm_lp[3];
-	uint32_t wm_lp_spr[3];
-	uint32_t wm_linetime[3];
-	bool enable_fbc_wm;
-};
-
 /* used in computing the new watermarks state */
 struct intel_wm_config {
 	unsigned int num_pipes_active;
@@ -2712,12 +2704,14 @@ static int ilk_wm_lp_to_level(int wm_lp, const struct intel_pipe_wm *pipe_wm)
 
 static void hsw_compute_wm_results(struct drm_device *dev,
 				   const struct intel_pipe_wm *merged,
+				   enum intel_ddb_partitioning partitioning,
 				   struct hsw_wm_values *results)
 {
 	struct intel_crtc *intel_crtc;
 	int level, wm_lp;
 
 	results->enable_fbc_wm = merged->fbc_wm_enabled;
+	results->partitioning = partitioning;
 
 	/* LP1+ register values */
 	for (wm_lp = 1; wm_lp <= 3; wm_lp++) {
@@ -2787,13 +2781,10 @@ static struct intel_pipe_wm *hsw_find_best_result(struct drm_device *dev,
  * causes WMs to be re-evaluated, expending some power.
  */
 static void hsw_write_wm_values(struct drm_i915_private *dev_priv,
-				struct hsw_wm_values *results,
-				enum intel_ddb_partitioning partitioning)
+				struct hsw_wm_values *results)
 {
 	struct hsw_wm_values previous;
 	uint32_t val;
-	enum intel_ddb_partitioning prev_partitioning;
-	bool prev_enable_fbc_wm;
 
 	previous.wm_pipe[0] = I915_READ(WM0_PIPEA_ILK);
 	previous.wm_pipe[1] = I915_READ(WM0_PIPEB_ILK);
@@ -2808,21 +2799,12 @@ static void hsw_write_wm_values(struct drm_i915_private *dev_priv,
 	previous.wm_linetime[1] = I915_READ(PIPE_WM_LINETIME(PIPE_B));
 	previous.wm_linetime[2] = I915_READ(PIPE_WM_LINETIME(PIPE_C));
 
-	prev_partitioning = (I915_READ(WM_MISC) & WM_MISC_DATA_PARTITION_5_6) ?
+	previous.partitioning = (I915_READ(WM_MISC) & WM_MISC_DATA_PARTITION_5_6) ?
 				INTEL_DDB_PART_5_6 : INTEL_DDB_PART_1_2;
 
-	prev_enable_fbc_wm = !(I915_READ(DISP_ARB_CTL) & DISP_FBC_WM_DIS);
-
-	if (memcmp(results->wm_pipe, previous.wm_pipe,
-		   sizeof(results->wm_pipe)) == 0 &&
-	    memcmp(results->wm_lp, previous.wm_lp,
-		   sizeof(results->wm_lp)) == 0 &&
-	    memcmp(results->wm_lp_spr, previous.wm_lp_spr,
-		   sizeof(results->wm_lp_spr)) == 0 &&
-	    memcmp(results->wm_linetime, previous.wm_linetime,
-		   sizeof(results->wm_linetime)) == 0 &&
-	    partitioning == prev_partitioning &&
-	    results->enable_fbc_wm == prev_enable_fbc_wm)
+	previous.enable_fbc_wm = !(I915_READ(DISP_ARB_CTL) & DISP_FBC_WM_DIS);
+
+	if (memcmp(results, &previous, sizeof(*results)) == 0)
 		return;
 
 	if (previous.wm_lp[2] != 0)
@@ -2846,16 +2828,16 @@ static void hsw_write_wm_values(struct drm_i915_private *dev_priv,
 	if (previous.wm_linetime[2] != results->wm_linetime[2])
 		I915_WRITE(PIPE_WM_LINETIME(PIPE_C), results->wm_linetime[2]);
 
-	if (prev_partitioning != partitioning) {
+	if (previous.partitioning != results->partitioning) {
 		val = I915_READ(WM_MISC);
-		if (partitioning == INTEL_DDB_PART_1_2)
+		if (results->partitioning == INTEL_DDB_PART_1_2)
 			val &= ~WM_MISC_DATA_PARTITION_5_6;
 		else
 			val |= WM_MISC_DATA_PARTITION_5_6;
 		I915_WRITE(WM_MISC, val);
 	}
 
-	if (prev_enable_fbc_wm != results->enable_fbc_wm) {
+	if (previous.enable_fbc_wm != results->enable_fbc_wm) {
 		val = I915_READ(DISP_ARB_CTL);
 		if (results->enable_fbc_wm)
 			val &= ~DISP_FBC_WM_DIS;
@@ -2877,6 +2859,8 @@ static void hsw_write_wm_values(struct drm_i915_private *dev_priv,
 		I915_WRITE(WM2_LP_ILK, results->wm_lp[1]);
 	if (results->wm_lp[2] != 0)
 		I915_WRITE(WM3_LP_ILK, results->wm_lp[2]);
+
+	dev_priv->wm.hw = *results;
 }
 
 static void haswell_update_wm(struct drm_crtc *crtc)
@@ -2914,12 +2898,12 @@ static void haswell_update_wm(struct drm_crtc *crtc)
 		best_lp_wm = &lp_wm_1_2;
 	}
 
-	hsw_compute_wm_results(dev, best_lp_wm, &results);
-
 	partitioning = (best_lp_wm == &lp_wm_1_2) ?
 		       INTEL_DDB_PART_1_2 : INTEL_DDB_PART_5_6;
 
-	hsw_write_wm_values(dev_priv, &results, partitioning);
+	hsw_compute_wm_results(dev, best_lp_wm, partitioning, &results);
+
+	hsw_write_wm_values(dev_priv, &results);
 }
 
 static void haswell_update_sprite_wm(struct drm_plane *plane,