drm/i915: consolidate pch pll enable sequence

It's been splattered over 3 different places all doing random things.
Now we have (mostly) the same sequence as i8xx/i9xx, but all called
from the crtc_enable hook (through the pll->enable function):
- write new dividers
- enable vco and wait for stable clocks
- write again for the pixel mutliplier

I've left the seemingly random 200 usec delay in there, just in case.

Also move the encoder->pre_pll_enable hook into the crtc_enable
function, at the same spot we currently have a hack to enable the lvds
port. Since that hack is now redundant, kill it.

While doing this patch I've learned the hard way that we can only fire
up the LVDS port if both the pch dpll _and_ the fdi rc pll are not yet
enabled. Otherwise things go haywire, at least on cpt.

v2: It is paramount to write the FPx divisors before we enable the
the vco by writing to the DPLL registers, for otherwise the divisors
won't get updated. This is in line with the i8xx/i9xx dpll.

v3: To keep the nice abstraction add a ->mode_set callback to set the
divisors. Also streamline the enabling/disabling code a bit by
removing some cargo-cult duplication and clearing registers where
possible in the ->disable hook.

v4: Remove now unused local variable.

Acked-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -156,6 +156,8 @@ struct intel_shared_dpll {
 	/* should match the index in the dev_priv->shared_dplls array */
 	enum intel_dpll_id id;
 	struct intel_dpll_hw_state hw_state;
+	void (*mode_set)(struct drm_i915_private *dev_priv,
+			 struct intel_shared_dpll *pll);
 	void (*enable)(struct drm_i915_private *dev_priv,
 		       struct intel_shared_dpll *pll);
 	void (*disable)(struct drm_i915_private *dev_priv,

drivers/gpu/drm/i915/intel_display.c

@@ -3096,13 +3096,7 @@ found:
 		WARN_ON(pll->on);
 		assert_shared_dpll_disabled(dev_priv, pll);
 
-		/* Wait for the clocks to stabilize before rewriting the regs */
-		I915_WRITE(PCH_DPLL(pll->id), dpll & ~DPLL_VCO_ENABLE);
-		POSTING_READ(PCH_DPLL(pll->id));
-		udelay(150);
-
-		I915_WRITE(PCH_FP0(pll->id), fp);
-		I915_WRITE(PCH_DPLL(pll->id), dpll & ~DPLL_VCO_ENABLE);
+		pll->mode_set(dev_priv, pll);
 	}
 	pll->refcount++;
 
@@ -3174,7 +3168,6 @@ static void ironlake_crtc_enable(struct drm_crtc *crtc)
 	struct intel_encoder *encoder;
 	int pipe = intel_crtc->pipe;
 	int plane = intel_crtc->plane;
-	u32 temp;
 
 	WARN_ON(!crtc->enabled);
 
@@ -3188,12 +3181,9 @@ static void ironlake_crtc_enable(struct drm_crtc *crtc)
 
 	intel_update_watermarks(dev);
 
-	if (intel_pipe_has_type(crtc, INTEL_OUTPUT_LVDS)) {
-		temp = I915_READ(PCH_LVDS);
-		if ((temp & LVDS_PORT_EN) == 0)
-			I915_WRITE(PCH_LVDS, temp | LVDS_PORT_EN);
-	}
-
+	for_each_encoder_on_crtc(dev, crtc, encoder)
+		if (encoder->pre_pll_enable)
+			encoder->pre_pll_enable(encoder);
 
 	if (intel_crtc->config.has_pch_encoder) {
 		/* Note: FDI PLL enabling _must_ be done before we enable the
@@ -5723,10 +5713,6 @@ static int ironlake_crtc_mode_set(struct drm_crtc *crtc,
 	if (intel_crtc->config.has_dp_encoder)
 		intel_dp_set_m_n(intel_crtc);
 
-	for_each_encoder_on_crtc(dev, crtc, encoder)
-		if (encoder->pre_pll_enable)
-			encoder->pre_pll_enable(encoder);
-
 	if (is_lvds && has_reduced_clock && i915_powersave)
 		intel_crtc->lowfreq_avail = true;
 	else
@@ -5735,23 +5721,6 @@ static int ironlake_crtc_mode_set(struct drm_crtc *crtc,
 	if (intel_crtc->config.has_pch_encoder) {
 		pll = intel_crtc_to_shared_dpll(intel_crtc);
 
-		I915_WRITE(PCH_DPLL(pll->id), dpll);
-
-		/* Wait for the clocks to stabilize. */
-		POSTING_READ(PCH_DPLL(pll->id));
-		udelay(150);
-
-		/* The pixel multiplier can only be updated once the
-		 * DPLL is enabled and the clocks are stable.
-		 *
-		 * So write it again.
-		 */
-		I915_WRITE(PCH_DPLL(pll->id), dpll);
-
-		if (has_reduced_clock)
-			I915_WRITE(PCH_FP1(pll->id), fp2);
-		else
-			I915_WRITE(PCH_FP1(pll->id), fp);
 	}
 
 	intel_set_pipe_timings(intel_crtc);
@@ -8800,19 +8769,32 @@ static bool ibx_pch_dpll_get_hw_state(struct drm_i915_private *dev_priv,
 	return val & DPLL_VCO_ENABLE;
 }
 
+static void ibx_pch_dpll_mode_set(struct drm_i915_private *dev_priv,
+				  struct intel_shared_dpll *pll)
+{
+	I915_WRITE(PCH_FP0(pll->id), pll->hw_state.fp0);
+	I915_WRITE(PCH_FP1(pll->id), pll->hw_state.fp1);
+}
+
 static void ibx_pch_dpll_enable(struct drm_i915_private *dev_priv,
 				struct intel_shared_dpll *pll)
 {
-	uint32_t reg, val;
-
 	/* PCH refclock must be enabled first */
 	assert_pch_refclk_enabled(dev_priv);
 
-	reg = PCH_DPLL(pll->id);
-	val = I915_READ(reg);
-	val |= DPLL_VCO_ENABLE;
-	I915_WRITE(reg, val);
-	POSTING_READ(reg);
+	I915_WRITE(PCH_DPLL(pll->id), pll->hw_state.dpll);
+
+	/* Wait for the clocks to stabilize. */
+	POSTING_READ(PCH_DPLL(pll->id));
+	udelay(150);
+
+	/* The pixel multiplier can only be updated once the
+	 * DPLL is enabled and the clocks are stable.
+	 *
+	 * So write it again.
+	 */
+	I915_WRITE(PCH_DPLL(pll->id), pll->hw_state.dpll);
+	POSTING_READ(PCH_DPLL(pll->id));
 	udelay(200);
 }
 
@@ -8821,7 +8803,6 @@ static void ibx_pch_dpll_disable(struct drm_i915_private *dev_priv,
 {
 	struct drm_device *dev = dev_priv->dev;
 	struct intel_crtc *crtc;
-	uint32_t reg, val;
 
 	/* Make sure no transcoder isn't still depending on us. */
 	list_for_each_entry(crtc, &dev->mode_config.crtc_list, base.head) {
@@ -8829,11 +8810,8 @@ static void ibx_pch_dpll_disable(struct drm_i915_private *dev_priv,
 			assert_pch_transcoder_disabled(dev_priv, crtc->pipe);
 	}
 
-	reg = PCH_DPLL(pll->id);
-	val = I915_READ(reg);
-	val &= ~DPLL_VCO_ENABLE;
-	I915_WRITE(reg, val);
-	POSTING_READ(reg);
+	I915_WRITE(PCH_DPLL(pll->id), 0);
+	POSTING_READ(PCH_DPLL(pll->id));
 	udelay(200);
 }
 
@@ -8852,6 +8830,7 @@ static void ibx_pch_dpll_init(struct drm_device *dev)
 	for (i = 0; i < dev_priv->num_shared_dpll; i++) {
 		dev_priv->shared_dplls[i].id = i;
 		dev_priv->shared_dplls[i].name = ibx_pch_dpll_names[i];
+		dev_priv->shared_dplls[i].mode_set = ibx_pch_dpll_mode_set;
 		dev_priv->shared_dplls[i].enable = ibx_pch_dpll_enable;
 		dev_priv->shared_dplls[i].disable = ibx_pch_dpll_disable;
 		dev_priv->shared_dplls[i].get_hw_state =