drm/i915: allow re-use BIOS connector config for initial fbdev config v3

The BIOS or boot loader will generally create an initial display
configuration for us that includes some set of active pipes and
displays.  This routine tries to figure out which pipes and connectors
are active and stuffs them into the crtcs and modes array given to us by
the drm_fb_helper code.

The overall sequence is:
  intel_fbdev_init - from driver load
    intel_fbdev_init_bios - initialize the intel_fbdev using BIOS data
    drm_fb_helper_init - build fb helper structs
    drm_fb_helper_single_add_all_connectors - more fb helper structs
  intel_fbdev_initial_config - apply the config
    drm_fb_helper_initial_config - call ->probe then register_framebuffer()
        drm_setup_crtcs - build crtc config for fbdev
          intel_fb_initial_config - find active connectors etc
        drm_fb_helper_single_fb_probe - set up fbdev
          intelfb_create - re-use or alloc fb, build out fbdev structs

v2: use BIOS connector config unconditionally if possible (Daniel)
    check for crtc cloning and reject (Daniel)
    fix up comments (Daniel)
v3: use command line args and preferred modes first (Ville)
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Tested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
[danvet: Re-add the WARN_ON for a missing encoder crtc - the state
sanitizer should take care of this. And spell-ocd the comments.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -51,7 +51,10 @@ static void ironlake_pch_clock_get(struct intel_crtc *crtc,
 
 static int intel_set_mode(struct drm_crtc *crtc, struct drm_display_mode *mode,
 			  int x, int y, struct drm_framebuffer *old_fb);
-
+static int intel_framebuffer_init(struct drm_device *dev,
+				  struct intel_framebuffer *ifb,
+				  struct drm_mode_fb_cmd2 *mode_cmd,
+				  struct drm_i915_gem_object *obj);
 
 typedef struct {
 	int	min, max;
@@ -7692,11 +7695,6 @@ static struct drm_display_mode load_detect_mode = {
 		 704, 832, 0, 480, 489, 491, 520, 0, DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC),
 };
 
-static int intel_framebuffer_init(struct drm_device *dev,
-				  struct intel_framebuffer *ifb,
-				  struct drm_mode_fb_cmd2 *mode_cmd,
-				  struct drm_i915_gem_object *obj);
-
 struct drm_framebuffer *
 __intel_framebuffer_create(struct drm_device *dev,
 			   struct drm_mode_fb_cmd2 *mode_cmd,

drivers/gpu/drm/i915/intel_fbdev.c

@@ -242,7 +242,130 @@ static void intel_crtc_fb_gamma_get(struct drm_crtc *crtc, u16 *red, u16 *green,
 	*blue = intel_crtc->lut_b[regno] << 8;
 }
 
+static struct drm_fb_helper_crtc *
+intel_fb_helper_crtc(struct drm_fb_helper *fb_helper, struct drm_crtc *crtc)
+{
+	int i;
+
+	for (i = 0; i < fb_helper->crtc_count; i++)
+		if (fb_helper->crtc_info[i].mode_set.crtc == crtc)
+			return &fb_helper->crtc_info[i];
+
+	return NULL;
+}
+
+/*
+ * Try to read the BIOS display configuration and use it for the initial
+ * fb configuration.
+ *
+ * The BIOS or boot loader will generally create an initial display
+ * configuration for us that includes some set of active pipes and displays.
+ * This routine tries to figure out which pipes and connectors are active
+ * and stuffs them into the crtcs and modes array given to us by the
+ * drm_fb_helper code.
+ *
+ * The overall sequence is:
+ *   intel_fbdev_init - from driver load
+ *     intel_fbdev_init_bios - initialize the intel_fbdev using BIOS data
+ *     drm_fb_helper_init - build fb helper structs
+ *     drm_fb_helper_single_add_all_connectors - more fb helper structs
+ *   intel_fbdev_initial_config - apply the config
+ *     drm_fb_helper_initial_config - call ->probe then register_framebuffer()
+ *         drm_setup_crtcs - build crtc config for fbdev
+ *           intel_fb_initial_config - find active connectors etc
+ *         drm_fb_helper_single_fb_probe - set up fbdev
+ *           intelfb_create - re-use or alloc fb, build out fbdev structs
+ *
+ * Note that we don't make special consideration whether we could actually
+ * switch to the selected modes without a full modeset. E.g. when the display
+ * is in VGA mode we need to recalculate watermarks and set a new high-res
+ * framebuffer anyway.
+ */
+static bool intel_fb_initial_config(struct drm_fb_helper *fb_helper,
+				    struct drm_fb_helper_crtc **crtcs,
+				    struct drm_display_mode **modes,
+				    bool *enabled, int width, int height)
+{
+	int i, j;
+
+	for (i = 0; i < fb_helper->connector_count; i++) {
+		struct drm_fb_helper_connector *fb_conn;
+		struct drm_connector *connector;
+		struct drm_encoder *encoder;
+		struct drm_fb_helper_crtc *new_crtc;
+
+		fb_conn = fb_helper->connector_info[i];
+		connector = fb_conn->connector;
+		if (!enabled[i]) {
+			DRM_DEBUG_KMS("connector %d not enabled, skipping\n",
+				      connector->base.id);
+			continue;
+		}
+
+		encoder = connector->encoder;
+		if (!encoder || WARN_ON(!encoder->crtc)) {
+			DRM_DEBUG_KMS("connector %d has no encoder or crtc, skipping\n",
+				      connector->base.id);
+			enabled[i] = false;
+			continue;
+		}
+
+		new_crtc = intel_fb_helper_crtc(fb_helper, encoder->crtc);
+
+		/*
+		 * Make sure we're not trying to drive multiple connectors
+		 * with a single CRTC, since our cloning support may not
+		 * match the BIOS.
+		 */
+		for (j = 0; j < fb_helper->connector_count; j++) {
+			if (crtcs[j] == new_crtc)
+				return false;
+		}
+
+		DRM_DEBUG_KMS("looking for cmdline mode on connector %d\n",
+			      fb_conn->connector->base.id);
+
+		/* go for command line mode first */
+		modes[i] = drm_pick_cmdline_mode(fb_conn, width, height);
+
+		/* try for preferred next */
+		if (!modes[i]) {
+			DRM_DEBUG_KMS("looking for preferred mode on connector %d\n",
+				      fb_conn->connector->base.id);
+			modes[i] = drm_has_preferred_mode(fb_conn, width,
+							  height);
+		}
+
+		/* last resort: use current mode */
+		if (!modes[i]) {
+			/*
+			 * IMPORTANT: We want to use the adjusted mode (i.e.
+			 * after the panel fitter upscaling) as the initial
+			 * config, not the input mode, which is what crtc->mode
+			 * usually contains. But since our current fastboot
+			 * code puts a mode derived from the post-pfit timings
+			 * into crtc->mode this works out correctly. We don't
+			 * use hwmode anywhere right now, so use it for this
+			 * since the fb helper layer wants a pointer to
+			 * something we own.
+			 */
+			intel_mode_from_pipe_config(&encoder->crtc->hwmode,
+						    &to_intel_crtc(encoder->crtc)->config);
+			modes[i] = &encoder->crtc->hwmode;
+		}
+		crtcs[i] = new_crtc;
+
+		DRM_DEBUG_KMS("connector %s on crtc %d: %s\n",
+			      drm_get_connector_name(connector),
+			      encoder->crtc->base.id,
+			      modes[i]->name);
+	}
+
+	return true;
+}
+
 static struct drm_fb_helper_funcs intel_fb_helper_funcs = {
+	.initial_config = intel_fb_initial_config,
 	.gamma_set = intel_crtc_fb_gamma_set,
 	.gamma_get = intel_crtc_fb_gamma_get,
 	.fb_probe = intelfb_create,