drm/i915: read out the modeset hw state at load and resume time

... instead of resetting a few things and hoping that this will work
out.

To properly disable the output pipelines at the initial modeset after
resume or boot up we need to have an accurate picture of which outputs
are enabled and connected to which crtcs. Otherwise we risk disabling
things at the wrong time, which can lead to hangs (or at least royally
confused panels), both requiring a walk to the reset button to fix.

Hence read out the hw state with the freshly introduce get_hw_state
functions and then sanitize it afterwards.

For a full modeset readout (which would allow us to avoid the initial
modeset at boot up) a few things are still missing:
- Reading out the mode from the pipe, especially the dotclock
  computation is quite some fun.
- Reading out the parameters for the stolen memory framebuffer and
  wrapping it up.
- Reading out the pch pll connections - luckily the disable code
  simply bails out if the crtc doesn't have a pch pll attached (even
  for configurations that would need one).

This patch here turned up tons of smelly stuff around resume: We
restore tons of register in seemingly random way (well, not quite, but
we're not too careful either), which leaves the hw in a rather
ill-defined state: E.g. the port registers are sometimes
unconditionally restore (lvds, crt), leaving us with an active
encoder/connector but no active pipe connected to it. Luckily the hw
state sanitizer detects this madness and fixes things up a bit.

v2: When checking whether an encoder with active connectors has a crtc
wire up to it, check for both the crtc _and_ it's active state.

v3:
- Extract intel_sanitize_encoder.
- Manually disable active encoders without an active pipe.

v4: Correclty fix up the pipe<->plane mapping on machines where we
switch pipes/planes. Noticed by Chris Wilson, who also provided the
fixup.

v5: Spelling fix in a comment, noticed by Paulo Zanoni

Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.c

@@ -543,6 +543,7 @@ static int i915_drm_thaw(struct drm_device *dev)
 		mutex_unlock(&dev->struct_mutex);
 
 		intel_modeset_init_hw(dev);
+		intel_modeset_setup_hw_state(dev);
 		drm_mode_config_reset(dev);
 		drm_irq_install(dev);
 

drivers/gpu/drm/i915/i915_drv.h

@@ -1539,6 +1539,7 @@ extern void intel_modeset_init(struct drm_device *dev);
 extern void intel_modeset_gem_init(struct drm_device *dev);
 extern void intel_modeset_cleanup(struct drm_device *dev);
 extern int intel_modeset_vga_set_state(struct drm_device *dev, bool state);
+extern void intel_modeset_setup_hw_state(struct drm_device *dev);
 extern bool intel_fbc_enabled(struct drm_device *dev);
 extern void intel_disable_fbc(struct drm_device *dev);
 extern bool ironlake_set_drps(struct drm_device *dev, u8 val);

drivers/gpu/drm/i915/intel_display.c

@@ -3589,7 +3589,7 @@ void intel_connector_dpms(struct drm_connector *connector, int mode)
  * of the connector. */
 bool intel_connector_get_hw_state(struct intel_connector *connector)
 {
-	enum pipe pipe;
+	enum pipe pipe = 0;
 	struct intel_encoder *encoder = connector->encoder;
 
 	return encoder->get_hw_state(encoder, &pipe);
@@ -6533,65 +6533,6 @@ free_work:
 	return ret;
 }
 
-static void intel_sanitize_modesetting(struct drm_device *dev,
-				       int pipe, int plane)
-{
-	struct drm_i915_private *dev_priv = dev->dev_private;
-	u32 reg, val;
-	int i;
-
-	/* Clear any frame start delays used for debugging left by the BIOS */
-	for_each_pipe(i) {
-		reg = PIPECONF(i);
-		I915_WRITE(reg, I915_READ(reg) & ~PIPECONF_FRAME_START_DELAY_MASK);
-	}
-
-	if (HAS_PCH_SPLIT(dev))
-		return;
-
-	/* Who knows what state these registers were left in by the BIOS or
-	 * grub?
-	 *
-	 * If we leave the registers in a conflicting state (e.g. with the
-	 * display plane reading from the other pipe than the one we intend
-	 * to use) then when we attempt to teardown the active mode, we will
-	 * not disable the pipes and planes in the correct order -- leaving
-	 * a plane reading from a disabled pipe and possibly leading to
-	 * undefined behaviour.
-	 */
-
-	reg = DSPCNTR(plane);
-	val = I915_READ(reg);
-
-	if ((val & DISPLAY_PLANE_ENABLE) == 0)
-		return;
-	if (!!(val & DISPPLANE_SEL_PIPE_MASK) == pipe)
-		return;
-
-	/* This display plane is active and attached to the other CPU pipe. */
-	pipe = !pipe;
-
-	/* Disable the plane and wait for it to stop reading from the pipe. */
-	intel_disable_plane(dev_priv, plane, pipe);
-	intel_disable_pipe(dev_priv, pipe);
-}
-
-static void intel_crtc_reset(struct drm_crtc *crtc)
-{
-	struct drm_device *dev = crtc->dev;
-	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
-
-	/* Reset flags back to the 'unknown' status so that they
-	 * will be correctly set on the initial modeset.
-	 */
-	intel_crtc->dpms_mode = -1;
-
-	/* We need to fix up any BIOS configuration that conflicts with
-	 * our expectations.
-	 */
-	intel_sanitize_modesetting(dev, intel_crtc->pipe, intel_crtc->plane);
-}
-
 static struct drm_crtc_helper_funcs intel_helper_funcs = {
 	.mode_set_base_atomic = intel_pipe_set_base_atomic,
 	.load_lut = intel_crtc_load_lut,
@@ -7006,7 +6947,6 @@ fail:
 }
 
 static const struct drm_crtc_funcs intel_crtc_funcs = {
-	.reset = intel_crtc_reset,
 	.cursor_set = intel_crtc_cursor_set,
 	.cursor_move = intel_crtc_cursor_move,
 	.gamma_set = intel_crtc_gamma_set,
@@ -7064,8 +7004,6 @@ static void intel_crtc_init(struct drm_device *dev, int pipe)
 	dev_priv->plane_to_crtc_mapping[intel_crtc->plane] = &intel_crtc->base;
 	dev_priv->pipe_to_crtc_mapping[intel_crtc->pipe] = &intel_crtc->base;
 
-	intel_crtc_reset(&intel_crtc->base);
-	intel_crtc->active = true; /* force the pipe off on setup_init_config */
 	intel_crtc->bpp = 24; /* default for pre-Ironlake */
 
 	drm_crtc_helper_add(&intel_crtc->base, &intel_helper_funcs);
@@ -7273,9 +7211,6 @@ static void intel_setup_outputs(struct drm_device *dev)
 			intel_encoder_clones(encoder);
 	}
 
-	/* disable all the possible outputs/crtcs before entering KMS mode */
-	drm_helper_disable_unused_functions(dev);
-
 	if (HAS_PCH_IBX(dev) || HAS_PCH_CPT(dev))
 		ironlake_init_pch_refclk(dev);
 }
@@ -7634,11 +7569,222 @@ void intel_modeset_init(struct drm_device *dev)
 	intel_setup_outputs(dev);
 }
 
+static void
+intel_connector_break_all_links(struct intel_connector *connector)
+{
+	connector->base.dpms = DRM_MODE_DPMS_OFF;
+	connector->base.encoder = NULL;
+	connector->encoder->connectors_active = false;
+	connector->encoder->base.crtc = NULL;
+}
+
+static void intel_sanitize_crtc(struct intel_crtc *crtc)
+{
+	struct drm_device *dev = crtc->base.dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	u32 reg, val;
+
+	/* Clear the dpms state for compatibility with code still using that
+	 * deprecated state variable. */
+	crtc->dpms_mode = -1;
+
+	/* Clear any frame start delays used for debugging left by the BIOS */
+	reg = PIPECONF(crtc->pipe);
+	I915_WRITE(reg, I915_READ(reg) & ~PIPECONF_FRAME_START_DELAY_MASK);
+
+	/* We need to sanitize the plane -> pipe mapping first because this will
+	 * disable the crtc (and hence change the state) if it is wrong. */
+	if (!HAS_PCH_SPLIT(dev)) {
+		struct intel_connector *connector;
+		bool plane;
+
+		reg = DSPCNTR(crtc->plane);
+		val = I915_READ(reg);
+
+		if ((val & DISPLAY_PLANE_ENABLE) == 0 &&
+		    (!!(val & DISPPLANE_SEL_PIPE_MASK) == crtc->pipe))
+			goto ok;
+
+		DRM_DEBUG_KMS("[CRTC:%d] wrong plane connection detected!\n",
+			      crtc->base.base.id);
+
+		/* Pipe has the wrong plane attached and the plane is active.
+		 * Temporarily change the plane mapping and disable everything
+		 * ...  */
+		plane = crtc->plane;
+		crtc->plane = !plane;
+		dev_priv->display.crtc_disable(&crtc->base);
+		crtc->plane = plane;
+
+		/* ... and break all links. */
+		list_for_each_entry(connector, &dev->mode_config.connector_list,
+				    base.head) {
+			if (connector->encoder->base.crtc != &crtc->base)
+				continue;
+
+			intel_connector_break_all_links(connector);
+		}
+
+		WARN_ON(crtc->active);
+		crtc->base.enabled = false;
+	}
+ok:
+
+	/* Adjust the state of the output pipe according to whether we
+	 * have active connectors/encoders. */
+	intel_crtc_update_dpms(&crtc->base);
+
+	if (crtc->active != crtc->base.enabled) {
+		struct intel_encoder *encoder;
+
+		/* This can happen either due to bugs in the get_hw_state
+		 * functions or because the pipe is force-enabled due to the
+		 * pipe A quirk. */
+		DRM_DEBUG_KMS("[CRTC:%d] hw state adjusted, was %s, now %s\n",
+			      crtc->base.base.id,
+			      crtc->base.enabled ? "enabled" : "disabled",
+			      crtc->active ? "enabled" : "disabled");
+
+		crtc->base.enabled = crtc->active;
+
+		/* Because we only establish the connector -> encoder ->
+		 * crtc links if something is active, this means the
+		 * crtc is now deactivated. Break the links. connector
+		 * -> encoder links are only establish when things are
+		 *  actually up, hence no need to break them. */
+		WARN_ON(crtc->active);
+
+		for_each_encoder_on_crtc(dev, &crtc->base, encoder) {
+			WARN_ON(encoder->connectors_active);
+			encoder->base.crtc = NULL;
+		}
+	}
+}
+
+static void intel_sanitize_encoder(struct intel_encoder *encoder)
+{
+	struct intel_connector *connector;
+	struct drm_device *dev = encoder->base.dev;
+
+	/* We need to check both for a crtc link (meaning that the
+	 * encoder is active and trying to read from a pipe) and the
+	 * pipe itself being active. */
+	bool has_active_crtc = encoder->base.crtc &&
+		to_intel_crtc(encoder->base.crtc)->active;
+
+	if (encoder->connectors_active && !has_active_crtc) {
+		DRM_DEBUG_KMS("[ENCODER:%d:%s] has active connectors but no active pipe!\n",
+			      encoder->base.base.id,
+			      drm_get_encoder_name(&encoder->base));
+
+		/* Connector is active, but has no active pipe. This is
+		 * fallout from our resume register restoring. Disable
+		 * the encoder manually again. */
+		if (encoder->base.crtc) {
+			DRM_DEBUG_KMS("[ENCODER:%d:%s] manually disabled\n",
+				      encoder->base.base.id,
+				      drm_get_encoder_name(&encoder->base));
+			encoder->disable(encoder);
+		}
+
+		/* Inconsistent output/port/pipe state happens presumably due to
+		 * a bug in one of the get_hw_state functions. Or someplace else
+		 * in our code, like the register restore mess on resume. Clamp
+		 * things to off as a safer default. */
+		list_for_each_entry(connector,
+				    &dev->mode_config.connector_list,
+				    base.head) {
+			if (connector->encoder != encoder)
+				continue;
+
+			intel_connector_break_all_links(connector);
+		}
+	}
+	/* Enabled encoders without active connectors will be fixed in
+	 * the crtc fixup. */
+}
+
+/* Scan out the current hw modeset state, sanitizes it and maps it into the drm
+ * and i915 state tracking structures. */
+void intel_modeset_setup_hw_state(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	enum pipe pipe;
+	u32 tmp;
+	struct intel_crtc *crtc;
+	struct intel_encoder *encoder;
+	struct intel_connector *connector;
+
+	for_each_pipe(pipe) {
+		crtc = to_intel_crtc(dev_priv->pipe_to_crtc_mapping[pipe]);
+
+		tmp = I915_READ(PIPECONF(pipe));
+		if (tmp & PIPECONF_ENABLE)
+			crtc->active = true;
+		else
+			crtc->active = false;
+
+		crtc->base.enabled = crtc->active;
+
+		DRM_DEBUG_KMS("[CRTC:%d] hw state readout: %s\n",
+			      crtc->base.base.id,
+			      crtc->active ? "enabled" : "disabled");
+	}
+
+	list_for_each_entry(encoder, &dev->mode_config.encoder_list,
+			    base.head) {
+		pipe = 0;
+
+		if (encoder->get_hw_state(encoder, &pipe)) {
+			encoder->base.crtc =
+				dev_priv->pipe_to_crtc_mapping[pipe];
+		} else {
+			encoder->base.crtc = NULL;
+		}
+
+		encoder->connectors_active = false;
+		DRM_DEBUG_KMS("[ENCODER:%d:%s] hw state readout: %s, pipe=%i\n",
+			      encoder->base.base.id,
+			      drm_get_encoder_name(&encoder->base),
+			      encoder->base.crtc ? "enabled" : "disabled",
+			      pipe);
+	}
+
+	list_for_each_entry(connector, &dev->mode_config.connector_list,
+			    base.head) {
+		if (connector->get_hw_state(connector)) {
+			connector->base.dpms = DRM_MODE_DPMS_ON;
+			connector->encoder->connectors_active = true;
+			connector->base.encoder = &connector->encoder->base;
+		} else {
+			connector->base.dpms = DRM_MODE_DPMS_OFF;
+			connector->base.encoder = NULL;
+		}
+		DRM_DEBUG_KMS("[CONNECTOR:%d:%s] hw state readout: %s\n",
+			      connector->base.base.id,
+			      drm_get_connector_name(&connector->base),
+			      connector->base.encoder ? "enabled" : "disabled");
+	}
+
+	/* HW state is read out, now we need to sanitize this mess. */
+	list_for_each_entry(encoder, &dev->mode_config.encoder_list,
+			    base.head) {
+		intel_sanitize_encoder(encoder);
+	}
+
+	for_each_pipe(pipe) {
+		crtc = to_intel_crtc(dev_priv->pipe_to_crtc_mapping[pipe]);
+		intel_sanitize_crtc(crtc);
+	}
+}
+
 void intel_modeset_gem_init(struct drm_device *dev)
 {
 	intel_modeset_init_hw(dev);
 
 	intel_setup_overlay(dev);
+
+	intel_modeset_setup_hw_state(dev);
 }
 
 void intel_modeset_cleanup(struct drm_device *dev)