drm/i915: Add infrastructure for choosing DPLLs before disabling crtcs

It is possible for a mode set to fail if there aren't shared DPLLS that
match the new configuration requirement or other errors in clock
computation. If that step is executed after disabling crtcs, in the
failure case the hardware configuration is changed and needs to be
restored. Doing those things early will allow the mode set to fail
before actually touching the hardware.

Follow up patches will convert different platforms to use the new
infrastructure.

v2: Keep pll->new_config valid only during mode set (Ville)
    Use kmemdup() in i915_shared_dpll_start_config() (Ville)
    Restore old pll config if something fails before commit (Ville)
    Don't set compute_clock hooks since dev_priv is kzalloc()'d (Ville)
Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -236,6 +236,8 @@ struct intel_shared_dpll_config {
 
 struct intel_shared_dpll {
 	struct intel_shared_dpll_config config;
+	struct intel_shared_dpll_config *new_config;
+
 	int active; /* count of number of active CRTCs (i.e. DPMS on) */
 	bool on; /* is the PLL actually active? Disabled during modeset */
 	const char *name;
@@ -484,6 +486,7 @@ struct drm_i915_display_funcs {
 				struct intel_crtc_config *);
 	void (*get_plane_config)(struct intel_crtc *,
 				 struct intel_plane_config *);
+	int (*crtc_compute_clock)(struct intel_crtc *crtc);
 	int (*crtc_mode_set)(struct intel_crtc *crtc,
 			     int x, int y,
 			     struct drm_framebuffer *old_fb);

drivers/gpu/drm/i915/intel_display.c

@@ -3863,15 +3863,9 @@ void intel_put_shared_dpll(struct intel_crtc *crtc)
 struct intel_shared_dpll *intel_get_shared_dpll(struct intel_crtc *crtc)
 {
 	struct drm_i915_private *dev_priv = crtc->base.dev->dev_private;
-	struct intel_shared_dpll *pll = intel_crtc_to_shared_dpll(crtc);
+	struct intel_shared_dpll *pll;
 	enum intel_dpll_id i;
 
-	if (pll) {
-		DRM_DEBUG_KMS("CRTC:%d dropping existing %s\n",
-			      crtc->base.base.id, pll->name);
-		intel_put_shared_dpll(crtc);
-	}
-
 	if (HAS_PCH_IBX(dev_priv->dev)) {
 		/* Ironlake PCH has a fixed PLL->PCH pipe mapping. */
 		i = (enum intel_dpll_id) crtc->pipe;
@@ -3880,7 +3874,7 @@ struct intel_shared_dpll *intel_get_shared_dpll(struct intel_crtc *crtc)
 		DRM_DEBUG_KMS("CRTC:%d using pre-allocated %s\n",
 			      crtc->base.base.id, pll->name);
 
-		WARN_ON(pll->config.crtc_mask);
+		WARN_ON(pll->new_config->crtc_mask);
 
 		goto found;
 	}
@@ -3889,17 +3883,16 @@ struct intel_shared_dpll *intel_get_shared_dpll(struct intel_crtc *crtc)
 		pll = &dev_priv->shared_dplls[i];
 
 		/* Only want to check enabled timings first */
-		if (pll->config.crtc_mask == 0)
+		if (pll->new_config->crtc_mask == 0)
 			continue;
 
-		if (memcmp(&crtc->config.dpll_hw_state,
-			   &pll->config.hw_state,
-			   sizeof(pll->config.hw_state)) == 0) {
-			DRM_DEBUG_KMS("CRTC:%d sharing existing %s "
-				      "(crtc_mask 0x%08x, active %d)\n",
+		if (memcmp(&crtc->new_config->dpll_hw_state,
+			   &pll->new_config->hw_state,
+			   sizeof(pll->new_config->hw_state)) == 0) {
+			DRM_DEBUG_KMS("CRTC:%d sharing existing %s (crtc mask 0x%08x, ative %d)\n",
 				      crtc->base.base.id, pll->name,
-				      pll->config.crtc_mask, pll->active);
-
+				      pll->new_config->crtc_mask,
+				      pll->active);
 			goto found;
 		}
 	}
@@ -3907,7 +3900,7 @@ struct intel_shared_dpll *intel_get_shared_dpll(struct intel_crtc *crtc)
 	/* Ok no matching timings, maybe there's a free one? */
 	for (i = 0; i < dev_priv->num_shared_dpll; i++) {
 		pll = &dev_priv->shared_dplls[i];
-		if (pll->config.crtc_mask == 0) {
+		if (pll->new_config->crtc_mask == 0) {
 			DRM_DEBUG_KMS("CRTC:%d allocated %s\n",
 				      crtc->base.base.id, pll->name);
 			goto found;
@@ -3917,18 +3910,85 @@ struct intel_shared_dpll *intel_get_shared_dpll(struct intel_crtc *crtc)
 	return NULL;
 
 found:
-	if (pll->config.crtc_mask == 0)
-		pll->config.hw_state = crtc->config.dpll_hw_state;
+	if (pll->new_config->crtc_mask == 0)
+		pll->new_config->hw_state = crtc->new_config->dpll_hw_state;
 
-	crtc->config.shared_dpll = i;
+	crtc->new_config->shared_dpll = i;
 	DRM_DEBUG_DRIVER("using %s for pipe %c\n", pll->name,
 			 pipe_name(crtc->pipe));
 
-	pll->config.crtc_mask |= 1 << crtc->pipe;
+	pll->new_config->crtc_mask |= 1 << crtc->pipe;
 
 	return pll;
 }
 
+/**
+ * intel_shared_dpll_start_config - start a new PLL staged config
+ * @dev_priv: DRM device
+ * @clear_pipes: mask of pipes that will have their PLLs freed
+ *
+ * Starts a new PLL staged config, copying the current config but
+ * releasing the references of pipes specified in clear_pipes.
+ */
+static int intel_shared_dpll_start_config(struct drm_i915_private *dev_priv,
+					  unsigned clear_pipes)
+{
+	struct intel_shared_dpll *pll;
+	enum intel_dpll_id i;
+
+	for (i = 0; i < dev_priv->num_shared_dpll; i++) {
+		pll = &dev_priv->shared_dplls[i];
+
+		pll->new_config = kmemdup(&pll->config, sizeof pll->config,
+					  GFP_KERNEL);
+		if (!pll->new_config)
+			goto cleanup;
+
+		pll->new_config->crtc_mask &= ~clear_pipes;
+	}
+
+	return 0;
+
+cleanup:
+	while (--i >= 0) {
+		pll = &dev_priv->shared_dplls[i];
+		pll->new_config = NULL;
+	}
+
+	return -ENOMEM;
+}
+
+static void intel_shared_dpll_commit(struct drm_i915_private *dev_priv)
+{
+	struct intel_shared_dpll *pll;
+	enum intel_dpll_id i;
+
+	for (i = 0; i < dev_priv->num_shared_dpll; i++) {
+		pll = &dev_priv->shared_dplls[i];
+
+		WARN_ON(pll->new_config == &pll->config);
+
+		pll->config = *pll->new_config;
+		kfree(pll->new_config);
+		pll->new_config = NULL;
+	}
+}
+
+static void intel_shared_dpll_abort_config(struct drm_i915_private *dev_priv)
+{
+	struct intel_shared_dpll *pll;
+	enum intel_dpll_id i;
+
+	for (i = 0; i < dev_priv->num_shared_dpll; i++) {
+		pll = &dev_priv->shared_dplls[i];
+
+		WARN_ON(pll->new_config == &pll->config);
+
+		kfree(pll->new_config);
+		pll->new_config = NULL;
+	}
+}
+
 static void cpt_verify_modeset(struct drm_device *dev, int pipe)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
@@ -5420,11 +5480,11 @@ static int intel_crtc_compute_config(struct intel_crtc *crtc,
 				     struct intel_crtc_config *pipe_config)
 {
 	struct drm_device *dev = crtc->base.dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct drm_display_mode *adjusted_mode = &pipe_config->adjusted_mode;
 
 	/* FIXME should check pixel clock limits on all platforms */
 	if (INTEL_INFO(dev)->gen < 4) {
-		struct drm_i915_private *dev_priv = dev->dev_private;
 		int clock_limit =
 			dev_priv->display.get_display_clock_speed(dev);
 
@@ -5474,10 +5534,11 @@ static int intel_crtc_compute_config(struct intel_crtc *crtc,
 		hsw_compute_ips_config(crtc, pipe_config);
 
 	/*
-	 * XXX: PCH/WRPLL clock sharing is done in ->mode_set, so make sure the
-	 * old clock survives for now.
+	 * XXX: PCH/WRPLL clock sharing is done in ->mode_set if ->compute_clock is not
+	 * set, so make sure the old clock survives for now.
 	 */
-	if (HAS_PCH_IBX(dev) || HAS_PCH_CPT(dev) || HAS_DDI(dev))
+	if (dev_priv->display.crtc_compute_clock == NULL &&
+            (HAS_PCH_IBX(dev) || HAS_PCH_CPT(dev) || HAS_DDI(dev)))
 		pipe_config->shared_dpll = crtc->config.shared_dpll;
 
 	if (pipe_config->has_pch_encoder)
@@ -7405,6 +7466,9 @@ static int ironlake_crtc_mode_set(struct intel_crtc *crtc,
 		else
 			crtc->new_config->dpll_hw_state.fp1 = fp;
 
+		if (intel_crtc_to_shared_dpll(crtc))
+			intel_put_shared_dpll(crtc);
+
 		pll = intel_get_shared_dpll(crtc);
 		if (pll == NULL) {
 			DRM_DEBUG_DRIVER("failed to find PLL for pipe %c\n",
@@ -10749,6 +10813,22 @@ static int __intel_set_mode(struct drm_crtc *crtc,
 		prepare_pipes &= ~disable_pipes;
 	}
 
+	if (dev_priv->display.crtc_compute_clock) {
+		unsigned clear_pipes = modeset_pipes | disable_pipes;
+
+		ret = intel_shared_dpll_start_config(dev_priv, clear_pipes);
+		if (ret)
+			goto done;
+
+		for_each_intel_crtc_masked(dev, modeset_pipes, intel_crtc) {
+			ret = dev_priv->display.crtc_compute_clock(intel_crtc);
+			if (ret) {
+				intel_shared_dpll_abort_config(dev_priv);
+				goto done;
+			}
+		}
+	}
+
 	for_each_intel_crtc_masked(dev, disable_pipes, intel_crtc)
 		intel_crtc_disable(&intel_crtc->base);
 
@@ -10776,6 +10856,9 @@ static int __intel_set_mode(struct drm_crtc *crtc,
 						&pipe_config->adjusted_mode);
 	}
 
+	if (dev_priv->display.crtc_compute_clock)
+		intel_shared_dpll_commit(dev_priv);
+
 	/* Only after disabling all output pipelines that will be changed can we
 	 * update the the output configuration. */
 	intel_modeset_update_state(dev, prepare_pipes);
@@ -10810,10 +10893,13 @@ static int __intel_set_mode(struct drm_crtc *crtc,
 		crtc->x = x;
 		crtc->y = y;
 
-		ret = dev_priv->display.crtc_mode_set(intel_crtc, x, y, fb);
+		if (dev_priv->display.crtc_mode_set) {
+			ret = dev_priv->display.crtc_mode_set(intel_crtc,
+							      x, y, fb);
 			if (ret)
 				goto done;
 		}
+	}
 
 	/* Now enable the clocks, plane, pipe, and connectors that we set up. */
 	for_each_intel_crtc_masked(dev, prepare_pipes, intel_crtc) {