[PATCH] drm/i915: Simplify the way BC bifurcation state consistency is kept

[Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>]

Remove the global modeset resource function that would disable the
bifurcation bit, and instead enable/disable it when enabling or
disabling the pch transcoder. The checks before the mode set should
ensure that the configuration is valid, so it should be safe to do it
so.

Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
---

On Mon, 2015-03-09 at 17:21 +0100, Daniel Vetter wrote:
> With atomic we need to probably look at crtc_state->mode_changed. As an
> interim solution we have the same information available in the
> modeset_pipes bitmask. I think replacing the check for intel_crtc->active
> with !(modeset_pipes & (1<<intel_crtc->pipe)) should work.

I looked into that solution, but involves passing modeset_pipes way down
into the call stack, so I started looking for a different solution. Do you
see any caveat with this approach?

Thanks,
Ander

---
 drivers/gpu/drm/i915/intel_display.c | 60 +++++++++++++-----------------------
 1 file changed, 21 insertions(+), 39 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 4008bf4..eca5a41 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -101,6 +101,8 @@ static void chv_prepare_pll(struct intel_crtc *crtc,
 			    const struct intel_crtc_state *pipe_config);
 static void intel_begin_crtc_commit(struct drm_crtc *crtc);
 static void intel_finish_crtc_commit(struct drm_crtc *crtc);
+static void ivybridge_update_fdi_bc_bifurcation(struct intel_crtc *intel_crtc,
+						bool pipe_active);
 
 static struct intel_encoder *intel_find_encoder(struct intel_connector *connector, int pipe)
 {
@@ -1956,6 +1958,8 @@ static void ironlake_disable_pch_transcoder(struct drm_i915_private *dev_priv,
 					    enum pipe pipe)
 {
 	struct drm_device *dev = dev_priv->dev;
+	struct intel_crtc *crtc =
+		to_intel_crtc(dev_priv->pipe_to_crtc_mapping[pipe]);
 	uint32_t reg, val;
 
 	/* FDI relies on the transcoder */
@@ -1980,6 +1984,9 @@ static void ironlake_disable_pch_transcoder(struct drm_i915_private *dev_priv,
 		val &= ~TRANS_CHICKEN2_TIMING_OVERRIDE;
 		I915_WRITE(reg, val);
 	}
+
+	if (IS_IVYBRIDGE(dev))
+		ivybridge_update_fdi_bc_bifurcation(crtc, false);
 }
 
 static void lpt_disable_pch_transcoder(struct drm_i915_private *dev_priv)
@@ -3153,32 +3160,6 @@ static bool pipe_has_enabled_pch(struct intel_crtc *crtc)
 	return crtc->base.state->enable && crtc->config->has_pch_encoder;
 }
 
-static void ivb_modeset_global_resources(struct drm_device *dev)
-{
-	struct drm_i915_private *dev_priv = dev->dev_private;
-	struct intel_crtc *pipe_B_crtc =
-		to_intel_crtc(dev_priv->pipe_to_crtc_mapping[PIPE_B]);
-	struct intel_crtc *pipe_C_crtc =
-		to_intel_crtc(dev_priv->pipe_to_crtc_mapping[PIPE_C]);
-	uint32_t temp;
-
-	/*
-	 * When everything is off disable fdi C so that we could enable fdi B
-	 * with all lanes. Note that we don't care about enabled pipes without
-	 * an enabled pch encoder.
-	 */
-	if (!pipe_has_enabled_pch(pipe_B_crtc) &&
-	    !pipe_has_enabled_pch(pipe_C_crtc)) {
-		WARN_ON(I915_READ(FDI_RX_CTL(PIPE_B)) & FDI_RX_ENABLE);
-		WARN_ON(I915_READ(FDI_RX_CTL(PIPE_C)) & FDI_RX_ENABLE);
-
-		temp = I915_READ(SOUTH_CHICKEN1);
-		temp &= ~FDI_BC_BIFURCATION_SELECT;
-		DRM_DEBUG_KMS("disabling fdi C rx\n");
-		I915_WRITE(SOUTH_CHICKEN1, temp);
-	}
-}
-
 /* The FDI link training functions for ILK/Ibexpeak. */
 static void ironlake_fdi_link_train(struct drm_crtc *crtc)
 {
@@ -3834,41 +3815,44 @@ static void ironlake_pch_transcoder_set_timings(struct intel_crtc *crtc,
 		   I915_READ(VSYNCSHIFT(cpu_transcoder)));
 }
 
-static void cpt_enable_fdi_bc_bifurcation(struct drm_device *dev)
+static void cpt_enable_fdi_bc_bifurcation(struct drm_device *dev, bool enable)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	uint32_t temp;
 
 	temp = I915_READ(SOUTH_CHICKEN1);
-	if (temp & FDI_BC_BIFURCATION_SELECT)
+	if (!!(temp & FDI_BC_BIFURCATION_SELECT) == enable)
 		return;
 
 	WARN_ON(I915_READ(FDI_RX_CTL(PIPE_B)) & FDI_RX_ENABLE);
 	WARN_ON(I915_READ(FDI_RX_CTL(PIPE_C)) & FDI_RX_ENABLE);
 
-	temp |= FDI_BC_BIFURCATION_SELECT;
-	DRM_DEBUG_KMS("enabling fdi C rx\n");
+	temp &= ~FDI_BC_BIFURCATION_SELECT;
+	if (enable)
+		temp |= FDI_BC_BIFURCATION_SELECT;
+
+	DRM_DEBUG_KMS("%sabling fdi C rx\n", enable ? "en" : "dis");
 	I915_WRITE(SOUTH_CHICKEN1, temp);
 	POSTING_READ(SOUTH_CHICKEN1);
 }
 
-static void ivybridge_update_fdi_bc_bifurcation(struct intel_crtc *intel_crtc)
+static void ivybridge_update_fdi_bc_bifurcation(struct intel_crtc *intel_crtc,
+						bool pipe_active)
 {
 	struct drm_device *dev = intel_crtc->base.dev;
-	struct drm_i915_private *dev_priv = dev->dev_private;
 
 	switch (intel_crtc->pipe) {
 	case PIPE_A:
 		break;
 	case PIPE_B:
-		if (intel_crtc->config->fdi_lanes > 2)
-			WARN_ON(I915_READ(SOUTH_CHICKEN1) & FDI_BC_BIFURCATION_SELECT);
+		if (intel_crtc->config->fdi_lanes > 2 && pipe_active)
+			cpt_enable_fdi_bc_bifurcation(dev, false);
 		else
-			cpt_enable_fdi_bc_bifurcation(dev);
+			cpt_enable_fdi_bc_bifurcation(dev, true);
 
 		break;
 	case PIPE_C:
-		cpt_enable_fdi_bc_bifurcation(dev);
+		cpt_enable_fdi_bc_bifurcation(dev, pipe_active);
 
 		break;
 	default:
@@ -3895,7 +3879,7 @@ static void ironlake_pch_enable(struct drm_crtc *crtc)
 	assert_pch_transcoder_disabled(dev_priv, pipe);
 
 	if (IS_IVYBRIDGE(dev))
-		ivybridge_update_fdi_bc_bifurcation(intel_crtc);
+		ivybridge_update_fdi_bc_bifurcation(intel_crtc, true);
 
 	/* Write the TU size bits before fdi link training, so that error
 	 * detection works. */
@@ -13056,8 +13040,6 @@ static void intel_init_display(struct drm_device *dev)
 	} else if (IS_IVYBRIDGE(dev)) {
 		/* FIXME: detect B0+ stepping and use auto training */
 		dev_priv->display.fdi_link_train = ivb_manual_fdi_link_train;
-		dev_priv->display.modeset_global_resources =
-			ivb_modeset_global_resources;
 	} else if (IS_HASWELL(dev) || IS_BROADWELL(dev)) {
 		dev_priv->display.fdi_link_train = hsw_fdi_link_train;
 	} else if (IS_VALLEYVIEW(dev)) {
-- 
2.1.0

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