drm/i915: Make {vlv,chv}_{disable,update}_pll() more similar

The VLV and CHV DPLL disable and update are almost identical in
how the DPLL/DPLL_MD registers need to be set up. But the code
looks more different than it really is. Try to bring them into
line.

Note that we now leave the refclock always enabled for both
DPLLs in the dual channel PHY. But that's perfectly fine since
it's the same clock, and we anyway already do that when turning
the disp2d power well on.

v2: s/chv_update_pll/chv_compute_dpll/
v3: Add a note that we leave refclocks enabled for both DPLLs (Jani)

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1458052809-23426-3-git-send-email-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/intel_display.c

@@ -1715,16 +1715,13 @@ static void vlv_disable_pll(struct drm_i915_private *dev_priv, enum pipe pipe)
 	/* Make sure the pipe isn't still relying on us */
 	assert_pipe_disabled(dev_priv, pipe);
 
-	/*
-	 * Leave integrated clock source and reference clock enabled for pipe B.
-	 * The latter is needed for VGA hotplug / manual detection.
-	 */
-	val = DPLL_VGA_MODE_DIS;
-	if (pipe == PIPE_B)
-		val = DPLL_INTEGRATED_CRI_CLK_VLV | DPLL_REF_CLK_ENABLE_VLV;
+	val = DPLL_INTEGRATED_REF_CLK_VLV |
+		DPLL_REF_CLK_ENABLE_VLV | DPLL_VGA_MODE_DIS;
+	if (pipe != PIPE_A)
+		val |= DPLL_INTEGRATED_CRI_CLK_VLV;
+
 	I915_WRITE(DPLL(pipe), val);
 	POSTING_READ(DPLL(pipe));
-
 }
 
 static void chv_disable_pll(struct drm_i915_private *dev_priv, enum pipe pipe)
@@ -1735,11 +1732,11 @@ static void chv_disable_pll(struct drm_i915_private *dev_priv, enum pipe pipe)
 	/* Make sure the pipe isn't still relying on us */
 	assert_pipe_disabled(dev_priv, pipe);
 
-	/* Set PLL en = 0 */
 	val = DPLL_SSC_REF_CLK_CHV |
 		DPLL_REF_CLK_ENABLE_VLV | DPLL_VGA_MODE_DIS;
 	if (pipe != PIPE_A)
 		val |= DPLL_INTEGRATED_CRI_CLK_VLV;
+
 	I915_WRITE(DPLL(pipe), val);
 	POSTING_READ(DPLL(pipe));
 
@@ -7156,24 +7153,27 @@ void intel_dp_set_m_n(struct intel_crtc *crtc, enum link_m_n_set m_n)
 static void vlv_compute_dpll(struct intel_crtc *crtc,
 			     struct intel_crtc_state *pipe_config)
 {
-	u32 dpll, dpll_md;
+	pipe_config->dpll_hw_state.dpll = DPLL_INTEGRATED_REF_CLK_VLV |
+		DPLL_REF_CLK_ENABLE_VLV | DPLL_VGA_MODE_DIS |
+		DPLL_VCO_ENABLE | DPLL_EXT_BUFFER_ENABLE_VLV;
+	if (crtc->pipe != PIPE_A)
+		pipe_config->dpll_hw_state.dpll |= DPLL_INTEGRATED_CRI_CLK_VLV;
 
-	/*
-	 * Enable DPIO clock input. We should never disable the reference
-	 * clock for pipe B, since VGA hotplug / manual detection depends
-	 * on it.
-	 */
-	dpll = DPLL_EXT_BUFFER_ENABLE_VLV | DPLL_REF_CLK_ENABLE_VLV |
-		DPLL_VGA_MODE_DIS | DPLL_INTEGRATED_REF_CLK_VLV;
-	/* We should never disable this, set it here for state tracking */
-	if (crtc->pipe == PIPE_B)
-		dpll |= DPLL_INTEGRATED_CRI_CLK_VLV;
-	dpll |= DPLL_VCO_ENABLE;
-	pipe_config->dpll_hw_state.dpll = dpll;
+	pipe_config->dpll_hw_state.dpll_md =
+		(pipe_config->pixel_multiplier - 1) << DPLL_MD_UDI_MULTIPLIER_SHIFT;
+}
+
+static void chv_compute_dpll(struct intel_crtc *crtc,
+			     struct intel_crtc_state *pipe_config)
+{
+	pipe_config->dpll_hw_state.dpll = DPLL_SSC_REF_CLK_CHV |
+		DPLL_REF_CLK_ENABLE_VLV | DPLL_VGA_MODE_DIS |
+		DPLL_VCO_ENABLE;
+	if (crtc->pipe != PIPE_A)
+		pipe_config->dpll_hw_state.dpll |= DPLL_INTEGRATED_CRI_CLK_VLV;
 
-	dpll_md = (pipe_config->pixel_multiplier - 1)
-		<< DPLL_MD_UDI_MULTIPLIER_SHIFT;
-	pipe_config->dpll_hw_state.dpll_md = dpll_md;
+	pipe_config->dpll_hw_state.dpll_md =
+		(pipe_config->pixel_multiplier - 1) << DPLL_MD_UDI_MULTIPLIER_SHIFT;
 }
 
 static void vlv_prepare_pll(struct intel_crtc *crtc,
@@ -7267,19 +7267,6 @@ static void vlv_prepare_pll(struct intel_crtc *crtc,
 	mutex_unlock(&dev_priv->sb_lock);
 }
 
-static void chv_compute_dpll(struct intel_crtc *crtc,
-			     struct intel_crtc_state *pipe_config)
-{
-	pipe_config->dpll_hw_state.dpll = DPLL_SSC_REF_CLK_CHV |
-		DPLL_REF_CLK_ENABLE_VLV | DPLL_VGA_MODE_DIS |
-		DPLL_VCO_ENABLE;
-	if (crtc->pipe != PIPE_A)
-		pipe_config->dpll_hw_state.dpll |= DPLL_INTEGRATED_CRI_CLK_VLV;
-
-	pipe_config->dpll_hw_state.dpll_md =
-		(pipe_config->pixel_multiplier - 1) << DPLL_MD_UDI_MULTIPLIER_SHIFT;
-}
-
 static void chv_prepare_pll(struct intel_crtc *crtc,
 			    const struct intel_crtc_state *pipe_config)
 {