drm/i915: Replace ironlake_compute_wm0 with g4x_compute_wm0

The computation of the first-level watermarks for g4x and gen5+ are
based on the same algorithm, so we can refactor those code paths to
use a single function.

Note that g4x_compute_wm0 takes a 'plane' argument while
ironlake_compute_wm0 took a 'pipe' argument. Both should have used a
'plane' argument, so this patch fixes that as well (not that it caused
a problem; ironlake always uses pipe == plane).
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Keith Packard <keithp@keithp.com>

drivers/gpu/drm/i915/intel_display.c

@@ -3983,54 +3983,6 @@ static void i830_update_wm(struct drm_device *dev)
 #define ILK_LP0_PLANE_LATENCY		700
 #define ILK_LP0_CURSOR_LATENCY		1300
 
-static bool ironlake_compute_wm0(struct drm_device *dev,
-				 int pipe,
-				 const struct intel_watermark_params *display,
-				 int display_latency_ns,
-				 const struct intel_watermark_params *cursor,
-				 int cursor_latency_ns,
-				 int *plane_wm,
-				 int *cursor_wm)
-{
-	struct drm_crtc *crtc;
-	int htotal, hdisplay, clock, pixel_size;
-	int line_time_us, line_count;
-	int entries, tlb_miss;
-
-	crtc = intel_get_crtc_for_pipe(dev, pipe);
-	if (crtc->fb == NULL || !crtc->enabled)
-		return false;
-
-	htotal = crtc->mode.htotal;
-	hdisplay = crtc->mode.hdisplay;
-	clock = crtc->mode.clock;
-	pixel_size = crtc->fb->bits_per_pixel / 8;
-
-	/* Use the small buffer method to calculate plane watermark */
-	entries = ((clock * pixel_size / 1000) * display_latency_ns) / 1000;
-	tlb_miss = display->fifo_size*display->cacheline_size - hdisplay * 8;
-	if (tlb_miss > 0)
-		entries += tlb_miss;
-	entries = DIV_ROUND_UP(entries, display->cacheline_size);
-	*plane_wm = entries + display->guard_size;
-	if (*plane_wm > (int)display->max_wm)
-		*plane_wm = display->max_wm;
-
-	/* Use the large buffer method to calculate cursor watermark */
-	line_time_us = ((htotal * 1000) / clock);
-	line_count = (cursor_latency_ns / line_time_us + 1000) / 1000;
-	entries = line_count * 64 * pixel_size;
-	tlb_miss = cursor->fifo_size*cursor->cacheline_size - hdisplay * 8;
-	if (tlb_miss > 0)
-		entries += tlb_miss;
-	entries = DIV_ROUND_UP(entries, cursor->cacheline_size);
-	*cursor_wm = entries + cursor->guard_size;
-	if (*cursor_wm > (int)cursor->max_wm)
-		*cursor_wm = (int)cursor->max_wm;
-
-	return true;
-}
-
 /*
  * Check the wm result.
  *
@@ -4139,12 +4091,12 @@ static void ironlake_update_wm(struct drm_device *dev)
 	unsigned int enabled;
 
 	enabled = 0;
-	if (ironlake_compute_wm0(dev, 0,
-				 &ironlake_display_wm_info,
-				 ILK_LP0_PLANE_LATENCY,
-				 &ironlake_cursor_wm_info,
-				 ILK_LP0_CURSOR_LATENCY,
-				 &plane_wm, &cursor_wm)) {
+	if (g4x_compute_wm0(dev, 0,
+			    &ironlake_display_wm_info,
+			    ILK_LP0_PLANE_LATENCY,
+			    &ironlake_cursor_wm_info,
+			    ILK_LP0_CURSOR_LATENCY,
+			    &plane_wm, &cursor_wm)) {
 		I915_WRITE(WM0_PIPEA_ILK,
 			   (plane_wm << WM0_PIPE_PLANE_SHIFT) | cursor_wm);
 		DRM_DEBUG_KMS("FIFO watermarks For pipe A -"
@@ -4153,12 +4105,12 @@ static void ironlake_update_wm(struct drm_device *dev)
 		enabled |= 1;
 	}
 
-	if (ironlake_compute_wm0(dev, 1,
-				 &ironlake_display_wm_info,
-				 ILK_LP0_PLANE_LATENCY,
-				 &ironlake_cursor_wm_info,
-				 ILK_LP0_CURSOR_LATENCY,
-				 &plane_wm, &cursor_wm)) {
+	if (g4x_compute_wm0(dev, 1,
+			    &ironlake_display_wm_info,
+			    ILK_LP0_PLANE_LATENCY,
+			    &ironlake_cursor_wm_info,
+			    ILK_LP0_CURSOR_LATENCY,
+			    &plane_wm, &cursor_wm)) {
 		I915_WRITE(WM0_PIPEB_ILK,
 			   (plane_wm << WM0_PIPE_PLANE_SHIFT) | cursor_wm);
 		DRM_DEBUG_KMS("FIFO watermarks For pipe B -"
@@ -4223,10 +4175,10 @@ static void sandybridge_update_wm(struct drm_device *dev)
 	unsigned int enabled;
 
 	enabled = 0;
-	if (ironlake_compute_wm0(dev, 0,
-				 &sandybridge_display_wm_info, latency,
-				 &sandybridge_cursor_wm_info, latency,
-				 &plane_wm, &cursor_wm)) {
+	if (g4x_compute_wm0(dev, 0,
+			    &sandybridge_display_wm_info, latency,
+			    &sandybridge_cursor_wm_info, latency,
+			    &plane_wm, &cursor_wm)) {
 		I915_WRITE(WM0_PIPEA_ILK,
 			   (plane_wm << WM0_PIPE_PLANE_SHIFT) | cursor_wm);
 		DRM_DEBUG_KMS("FIFO watermarks For pipe A -"
@@ -4235,10 +4187,10 @@ static void sandybridge_update_wm(struct drm_device *dev)
 		enabled |= 1;
 	}
 
-	if (ironlake_compute_wm0(dev, 1,
-				 &sandybridge_display_wm_info, latency,
-				 &sandybridge_cursor_wm_info, latency,
-				 &plane_wm, &cursor_wm)) {
+	if (g4x_compute_wm0(dev, 1,
+			    &sandybridge_display_wm_info, latency,
+			    &sandybridge_cursor_wm_info, latency,
+			    &plane_wm, &cursor_wm)) {
 		I915_WRITE(WM0_PIPEB_ILK,
 			   (plane_wm << WM0_PIPE_PLANE_SHIFT) | cursor_wm);
 		DRM_DEBUG_KMS("FIFO watermarks For pipe B -"