drm: initial KMS config fixes

When mode setting is first initialized, the driver will call into
drm_helper_initial_config() to set up an initial output and framebuffer
configuration.  This routine is responsible for probing the available
connectors, encoders, and crtcs, looking for modes and putting together
something reasonable (where reasonable is defined as "allows kernel
messages to be visible on as many displays as possible").

However, the code was a bit too aggressive in setting default modes when
none were found on a given connector.  Even if some connectors had modes,
any connectors found lacking modes would have the default 800x600 mode added
to their mode list, which in some cases could cause problems later down the
line.  In my case, the LVDS was perfectly available, but the initial config
code added 800x600 modes to both of the detected but unavailable HDMI
connectors (which are on my non-existent docking station).  This ended up
preventing later code from setting a mode on my LVDS, which is bad.

This patch fixes that behavior by making the initial config code walk
through the connectors first, counting the available modes, before it decides
to add any default modes to a possibly connected output.  It also fixes the
logic in drm_target_preferred() that was causing zeroed out modes to be set
as the preferred mode for a given connector, even if no modes were available.
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Dave Airlie <airlied@linux.ie>

drivers/gpu/drm/drm_crtc_helper.c

@@ -36,7 +36,7 @@
 /*
  * Detailed mode info for 800x600@60Hz
  */
-static struct drm_display_mode std_mode[] = {
+static struct drm_display_mode std_modes[] = {
 	{ DRM_MODE("800x600", DRM_MODE_TYPE_DEFAULT, 40000, 800, 840,
 		   968, 1056, 0, 600, 601, 605, 628, 0,
 		   DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC) },
@@ -60,15 +60,18 @@ static struct drm_display_mode std_mode[] = {
  * changes have occurred.
  *
  * FIXME: take into account monitor limits
+ *
+ * RETURNS:
+ * Number of modes found on @connector.
  */
-void drm_helper_probe_single_connector_modes(struct drm_connector *connector,
-					     uint32_t maxX, uint32_t maxY)
+int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
+					    uint32_t maxX, uint32_t maxY)
 {
 	struct drm_device *dev = connector->dev;
 	struct drm_display_mode *mode, *t;
 	struct drm_connector_helper_funcs *connector_funcs =
 		connector->helper_private;
-	int ret;
+	int count = 0;
 
 	DRM_DEBUG("%s\n", drm_get_connector_name(connector));
 	/* set all modes to the unverified state */
@@ -81,14 +84,14 @@ void drm_helper_probe_single_connector_modes(struct drm_connector *connector,
 		DRM_DEBUG("%s is disconnected\n",
 			  drm_get_connector_name(connector));
 		/* TODO set EDID to NULL */
-		return;
+		return 0;
 	}
 
-	ret = (*connector_funcs->get_modes)(connector);
+	count = (*connector_funcs->get_modes)(connector);
+	if (!count)
+		return 0;
 
-	if (ret) {
-		drm_mode_connector_list_update(connector);
-	}
+	drm_mode_connector_list_update(connector);
 
 	if (maxX && maxY)
 		drm_mode_validate_size(dev, &connector->modes, maxX,
@@ -102,25 +105,8 @@ void drm_helper_probe_single_connector_modes(struct drm_connector *connector,
 
 	drm_mode_prune_invalid(dev, &connector->modes, true);
 
-	if (list_empty(&connector->modes)) {
-		struct drm_display_mode *stdmode;
-
-		DRM_DEBUG("No valid modes on %s\n",
-			  drm_get_connector_name(connector));
-
-		/* Should we do this here ???
-		 * When no valid EDID modes are available we end up
-		 * here and bailed in the past, now we add a standard
-		 * 640x480@60Hz mode and carry on.
-		 */
-		stdmode = drm_mode_duplicate(dev, &std_mode[0]);
-		drm_mode_probed_add(connector, stdmode);
-		drm_mode_list_concat(&connector->probed_modes,
-				     &connector->modes);
-
-		DRM_DEBUG("Adding standard 640x480 @ 60Hz to %s\n",
-			  drm_get_connector_name(connector));
-	}
+	if (list_empty(&connector->modes))
+		return 0;
 
 	drm_mode_sort(&connector->modes);
 
@@ -131,20 +117,58 @@ void drm_helper_probe_single_connector_modes(struct drm_connector *connector,
 		drm_mode_set_crtcinfo(mode, CRTC_INTERLACE_HALVE_V);
 		drm_mode_debug_printmodeline(mode);
 	}
+
+	return count;
 }
 EXPORT_SYMBOL(drm_helper_probe_single_connector_modes);
 
-void drm_helper_probe_connector_modes(struct drm_device *dev, uint32_t maxX,
+int drm_helper_probe_connector_modes(struct drm_device *dev, uint32_t maxX,
 				      uint32_t maxY)
 {
 	struct drm_connector *connector;
+	int count = 0;
 
 	list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
-		drm_helper_probe_single_connector_modes(connector, maxX, maxY);
+		count += drm_helper_probe_single_connector_modes(connector,
+								 maxX, maxY);
 	}
+
+	return count;
 }
 EXPORT_SYMBOL(drm_helper_probe_connector_modes);
 
+static void drm_helper_add_std_modes(struct drm_device *dev,
+				     struct drm_connector *connector)
+{
+	struct drm_display_mode *mode, *t;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(std_modes); i++) {
+		struct drm_display_mode *stdmode;
+
+		/*
+		 * When no valid EDID modes are available we end up
+		 * here and bailed in the past, now we add some standard
+		 * modes and move on.
+		 */
+		stdmode = drm_mode_duplicate(dev, &std_modes[i]);
+		drm_mode_probed_add(connector, stdmode);
+		drm_mode_list_concat(&connector->probed_modes,
+				     &connector->modes);
+
+		DRM_DEBUG("Adding mode %s to %s\n", stdmode->name,
+			  drm_get_connector_name(connector));
+	}
+	drm_mode_sort(&connector->modes);
+
+	DRM_DEBUG("Added std modes on %s\n", drm_get_connector_name(connector));
+	list_for_each_entry_safe(mode, t, &connector->modes, head) {
+		mode->vrefresh = drm_mode_vrefresh(mode);
+
+		drm_mode_set_crtcinfo(mode, CRTC_INTERLACE_HALVE_V);
+		drm_mode_debug_printmodeline(mode);
+	}
+}
 
 /**
  * drm_helper_crtc_in_use - check if a given CRTC is in a mode_config
@@ -237,6 +261,8 @@ static void drm_enable_connectors(struct drm_device *dev, bool *enabled)
 
 	list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
 		enabled[i] = drm_connector_enabled(connector, true);
+		DRM_DEBUG("connector %d enabled? %s\n", connector->base.id,
+			  enabled[i] ? "yes" : "no");
 		any_enabled |= enabled[i];
 		i++;
 	}
@@ -265,11 +291,17 @@ static bool drm_target_preferred(struct drm_device *dev,
 			continue;
 		}
 
+		DRM_DEBUG("looking for preferred mode on connector %d\n",
+			  connector->base.id);
+
 		modes[i] = drm_has_preferred_mode(connector, width, height);
-		if (!modes[i]) {
+		/* No preferred modes, pick one off the list */
+		if (!modes[i] && !list_empty(&connector->modes)) {
 			list_for_each_entry(modes[i], &connector->modes, head)
 				break;
 		}
+		DRM_DEBUG("found mode %s\n", modes[i] ? modes[i]->name :
+			  "none");
 		i++;
 	}
 	return true;
@@ -369,6 +401,8 @@ static void drm_setup_crtcs(struct drm_device *dev)
 	int width, height;
 	int i, ret;
 
+	DRM_DEBUG("\n");
+
 	width = dev->mode_config.max_width;
 	height = dev->mode_config.max_height;
 
@@ -390,6 +424,8 @@ static void drm_setup_crtcs(struct drm_device *dev)
 	if (!ret)
 		DRM_ERROR("Unable to find initial modes\n");
 
+	DRM_DEBUG("picking CRTCs for %dx%d config\n", width, height);
+
 	drm_pick_crtcs(dev, crtcs, modes, 0, width, height);
 
 	i = 0;
@@ -403,6 +439,8 @@ static void drm_setup_crtcs(struct drm_device *dev)
 		}
 
 		if (mode && crtc) {
+			DRM_DEBUG("desired mode %s set on crtc %d\n",
+				  mode->name, crtc->base.id);
 			crtc->desired_mode = mode;
 			connector->encoder->crtc = crtc;
 		} else
@@ -764,10 +802,31 @@ bool drm_helper_plugged_event(struct drm_device *dev)
  */
 bool drm_helper_initial_config(struct drm_device *dev, bool can_grow)
 {
-	int ret = false;
+	struct drm_connector *connector;
+	int count = 0;
 
-	drm_helper_plugged_event(dev);
-	return ret;
+	count = drm_helper_probe_connector_modes(dev,
+						 dev->mode_config.max_width,
+						 dev->mode_config.max_height);
+
+	/*
+	 * None of the available connectors had any modes, so add some
+	 * and try to light them up anyway
+	 */
+	if (!count) {
+		DRM_ERROR("connectors have no modes, using standard modes\n");
+		list_for_each_entry(connector,
+				    &dev->mode_config.connector_list,
+				    head)
+			drm_helper_add_std_modes(dev, connector);
+	}
+
+	drm_setup_crtcs(dev);
+
+	/* alert the driver fb layer */
+	dev->mode_config.funcs->fb_changed(dev);
+
+	return 0;
 }
 EXPORT_SYMBOL(drm_helper_initial_config);
 

include/drm/drm_crtc.h

@@ -395,7 +395,7 @@ struct drm_connector_funcs {
 	void (*save)(struct drm_connector *connector);
 	void (*restore)(struct drm_connector *connector);
 	enum drm_connector_status (*detect)(struct drm_connector *connector);
-	void (*fill_modes)(struct drm_connector *connector, uint32_t max_width, uint32_t max_height);
+	int (*fill_modes)(struct drm_connector *connector, uint32_t max_width, uint32_t max_height);
 	int (*set_property)(struct drm_connector *connector, struct drm_property *property,
 			     uint64_t val);
 	void (*destroy)(struct drm_connector *connector);

include/drm/drm_crtc_helper.h

@@ -88,7 +88,7 @@ struct drm_connector_helper_funcs {
 	struct drm_encoder *(*best_encoder)(struct drm_connector *connector);
 };
 
-extern void drm_helper_probe_single_connector_modes(struct drm_connector *connector, uint32_t maxX, uint32_t maxY);
+extern int drm_helper_probe_single_connector_modes(struct drm_connector *connector, uint32_t maxX, uint32_t maxY);
 extern void drm_helper_disable_unused_functions(struct drm_device *dev);
 extern int drm_helper_hotplug_stage_two(struct drm_device *dev);
 extern bool drm_helper_initial_config(struct drm_device *dev, bool can_grow);