drm/i915: remove intel_update_linetime_watermarks

The spec says the linetime watermarks must be programmed before
enabling any display low power watermarks, but we're currently
updating the linetime watermarks after we call intel_update_watermarks
(and only at crtc_mode_set, not at crtc_{enable,disable}). So IMHO the
best way guarantee the linetime watermarks will be updated before the
low power watermarks is inside the update_wm function, because it's
the function that enables low power watermarks. And since Haswell is
the only platform that has linetime watermarks, let's completely kill
the "intel_update_linetime_watermarks" abstraction and just use the
intel_update_watermarks abstraction by creating haswell_update_wm.

For now haswell_update_wm is still calling sandybridge_update_wm, but
in the future I plan to implement a function specific to Haswell.

v2: - Rename patch
    - Disable LP watermarks before changing linetime WMs (Chris)
    - Add a comment explaining that this is just temporary code.
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -316,8 +316,6 @@ struct drm_i915_display_funcs {
 	void (*update_wm)(struct drm_device *dev);
 	void (*update_sprite_wm)(struct drm_device *dev, int pipe,
 				 uint32_t sprite_width, int pixel_size);
-	void (*update_linetime_wm)(struct drm_device *dev, int pipe,
-				 struct drm_display_mode *mode);
 	void (*modeset_global_resources)(struct drm_device *dev);
 	/* Returns the active state of the crtc, and if the crtc is active,
 	 * fills out the pipe-config with the hw state. */

drivers/gpu/drm/i915/intel_display.c

@@ -6008,8 +6008,6 @@ static int haswell_crtc_mode_set(struct drm_crtc *crtc,
 
 	intel_update_watermarks(dev);
 
-	intel_update_linetime_watermarks(dev, pipe, adjusted_mode);
-
 	return ret;
 }
 

drivers/gpu/drm/i915/intel_drv.h

@@ -732,8 +732,6 @@ extern void intel_update_watermarks(struct drm_device *dev);
 extern void intel_update_sprite_watermarks(struct drm_device *dev, int pipe,
 					   uint32_t sprite_width,
 					   int pixel_size);
-extern void intel_update_linetime_watermarks(struct drm_device *dev, int pipe,
-			 struct drm_display_mode *mode);
 
 extern unsigned long intel_gen4_compute_page_offset(int *x, int *y,
 						    unsigned int tiling_mode,

drivers/gpu/drm/i915/intel_pm.c

@@ -2073,12 +2073,19 @@ static void ivybridge_update_wm(struct drm_device *dev)
 }
 
 static void
-haswell_update_linetime_wm(struct drm_device *dev, int pipe,
-				 struct drm_display_mode *mode)
+haswell_update_linetime_wm(struct drm_device *dev, struct drm_crtc *crtc)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
+	enum pipe pipe = intel_crtc->pipe;
+	struct drm_display_mode *mode = &intel_crtc->config.adjusted_mode;
 	u32 temp;
 
+	if (!intel_crtc_active(crtc)) {
+		I915_WRITE(PIPE_WM_LINETIME(pipe), 0);
+		return;
+	}
+
 	temp = I915_READ(PIPE_WM_LINETIME(pipe));
 	temp &= ~PIPE_WM_LINETIME_MASK;
 
@@ -2099,6 +2106,26 @@ haswell_update_linetime_wm(struct drm_device *dev, int pipe,
 	I915_WRITE(PIPE_WM_LINETIME(pipe), temp);
 }
 
+static void haswell_update_wm(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct drm_crtc *crtc;
+	enum pipe pipe;
+
+	/* Disable the LP WMs before changine the linetime registers. This is
+	 * just a temporary code that will be replaced soon. */
+	I915_WRITE(WM3_LP_ILK, 0);
+	I915_WRITE(WM2_LP_ILK, 0);
+	I915_WRITE(WM1_LP_ILK, 0);
+
+	for_each_pipe(pipe) {
+		crtc = dev_priv->pipe_to_crtc_mapping[pipe];
+		haswell_update_linetime_wm(dev, crtc);
+	}
+
+	sandybridge_update_wm(dev);
+}
+
 static bool
 sandybridge_compute_sprite_wm(struct drm_device *dev, int plane,
 			      uint32_t sprite_width, int pixel_size,
@@ -2294,15 +2321,6 @@ void intel_update_watermarks(struct drm_device *dev)
 		dev_priv->display.update_wm(dev);
 }
 
-void intel_update_linetime_watermarks(struct drm_device *dev,
-		int pipe, struct drm_display_mode *mode)
-{
-	struct drm_i915_private *dev_priv = dev->dev_private;
-
-	if (dev_priv->display.update_linetime_wm)
-		dev_priv->display.update_linetime_wm(dev, pipe, mode);
-}
-
 void intel_update_sprite_watermarks(struct drm_device *dev, int pipe,
 				    uint32_t sprite_width, int pixel_size)
 {
@@ -4624,9 +4642,8 @@ void intel_init_pm(struct drm_device *dev)
 			dev_priv->display.init_clock_gating = ivybridge_init_clock_gating;
 		} else if (IS_HASWELL(dev)) {
 			if (SNB_READ_WM0_LATENCY()) {
-				dev_priv->display.update_wm = sandybridge_update_wm;
+				dev_priv->display.update_wm = haswell_update_wm;
 				dev_priv->display.update_sprite_wm = sandybridge_update_sprite_wm;
-				dev_priv->display.update_linetime_wm = haswell_update_linetime_wm;
 			} else {
 				DRM_DEBUG_KMS("Failed to read display plane latency. "
 					      "Disable CxSR\n");