drm/i915: add encoder->pre_pll_enable callback

Currently we have two encoder specific bits in the common mode_set
functions:
- lvds pin pair enabling
- dp m/n setting and computation

Now the lvds stuff needs to happen before the pll is enabled. Since
that is done in the crtc_mode_set functions, we need to add a new
callback to be able to move them to the encoder code (where they
belong). The dp m/n stuff is a giant mess anyway (since it also
confuses itself with the fdi link m/n handling), so that needs to be
handled separately.

I think that we can move the pll enabling down quite a bit, which
might allow us to eventually merge encoder->pre_enable with this new
pre_pll_enable callback. But for now this will allow us to clean
things up a bit.

Note that vlv doesn't support lvds, hence we don't need to change
anything in there.

v2: Fixup commit message, both suggested from Paulo Zanoni.
- dp m/n doesn't need to happen before pll enabling
- lvds doesn't exist on vlv, hence no changes required in the vlv pll
  function.
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -4464,6 +4464,7 @@ static void i9xx_update_pll(struct drm_crtc *crtc,
 	struct drm_device *dev = crtc->dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
+	struct intel_encoder *encoder;
 	int pipe = intel_crtc->pipe;
 	u32 dpll;
 	bool is_sdvo;
@@ -4532,6 +4533,10 @@ static void i9xx_update_pll(struct drm_crtc *crtc,
 	POSTING_READ(DPLL(pipe));
 	udelay(150);
 
+	for_each_encoder_on_crtc(dev, crtc, encoder)
+		if (encoder->pre_pll_enable)
+			encoder->pre_pll_enable(encoder);
+
 	/* The LVDS pin pair needs to be on before the DPLLs are enabled.
 	 * This is an exception to the general rule that mode_set doesn't turn
 	 * things on.
@@ -4576,6 +4581,7 @@ static void i8xx_update_pll(struct drm_crtc *crtc,
 	struct drm_device *dev = crtc->dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
+	struct intel_encoder *encoder;
 	int pipe = intel_crtc->pipe;
 	u32 dpll;
 
@@ -4609,6 +4615,10 @@ static void i8xx_update_pll(struct drm_crtc *crtc,
 	POSTING_READ(DPLL(pipe));
 	udelay(150);
 
+	for_each_encoder_on_crtc(dev, crtc, encoder)
+		if (encoder->pre_pll_enable)
+			encoder->pre_pll_enable(encoder);
+
 	/* The LVDS pin pair needs to be on before the DPLLs are enabled.
 	 * This is an exception to the general rule that mode_set doesn't turn
 	 * things on.
@@ -5537,6 +5547,10 @@ static int ironlake_crtc_mode_set(struct drm_crtc *crtc,
 		I915_WRITE(TRANSDPLINK_N1(pipe), 0);
 	}
 
+	for_each_encoder_on_crtc(dev, crtc, encoder)
+		if (encoder->pre_pll_enable)
+			encoder->pre_pll_enable(encoder);
+
 	if (intel_crtc->pch_pll) {
 		I915_WRITE(intel_crtc->pch_pll->pll_reg, dpll);
 

drivers/gpu/drm/i915/intel_drv.h

@@ -153,6 +153,7 @@ struct intel_encoder {
 	bool cloneable;
 	bool connectors_active;
 	void (*hot_plug)(struct intel_encoder *);
+	void (*pre_pll_enable)(struct intel_encoder *);
 	void (*pre_enable)(struct intel_encoder *);
 	void (*enable)(struct intel_encoder *);
 	void (*disable)(struct intel_encoder *);