drm/i915: Wrap the preallocated BIOS framebuffer and preserve for KMS fbcon v12

Retrieve current framebuffer config info from the regs and create an fb
object for the buffer the BIOS or boot loader left us.  This should
allow for smooth transitions to userspace apps once we finish the
initial configuration construction.

v2: check for non-native modes and adjust (Jesse)
    fixup aperture and cmap frees (Imre)
    use unlocked unref if init_bios fails (Jesse)
    fix curly brace around DSPADDR check (Imre)
    comment failure path for pin_and_fence (Imre)
v3: fixup fixup of aperture frees (Chris)
v4: update to current bits (locking & pin_and_fence hack) (Jesse)
v5: move fb config fetch to display code (Jesse)
    re-order hw state readout on initial load to suit fb inherit (Jesse)
    re-add pin_and_fence in fbdev code to make sure we refcount properly (Je
v6: rename to plane_config (Daniel)
    check for valid object when initializing BIOS fb (Jesse)
    split from plane_config readout and other display changes (Jesse)
    drop use_bios_fb option (Chris)
    update comments (Jesse)
    rework fbdev_init_bios for clarity (Jesse)
    drop fb obj ref under lock (Chris)
v7: use fb object from plane_config instead (Ville)
    take ref on fb object (Jesse)
v8: put under i915_fastboot option (Jesse)
    fix fb ptr checking (Jesse)
    inform drm_fb_helper if we fail to enable a connector (Jesse)
    drop unnecessary enabled[] modifications in failure cases (Chris)
    split from BIOS connector config readout (Daniel)
    don't memset the fb buffer if preallocated (Chris)
    alloc ifbdev up front and pass to init_bios (Chris)
    check for bad ifbdev in restore_mode too (Chris)
v9: fix up !fastboot bpp setting (Jesse)
    fix up !fastboot helper alloc (Jesse)
    make sure BIOS fb is sufficient for biggest active pipe (Jesse)
v10:fix up size calculation for proposed fbs (Chris)
    go back to two pass pipe fb assignment (Chris)
    add warning for active pipes w/o fbs (Chris)
    clean up num_pipes checks in fbdev_init and fbdev_restore_mode (Chris)
    move i915.fastboot into fbdev_init (Chris)
v11:make BIOS connector config usage unconditional (Daniel)
v12:fix up fb vs pipe size checking (Chris)
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -2108,7 +2108,6 @@ static void intel_alloc_plane_obj(struct intel_crtc *crtc,
 out_unref_obj:
 	drm_gem_object_unreference(&obj->base);
 	mutex_unlock(&dev->struct_mutex);
-
 }
 
 static int i9xx_update_plane(struct drm_crtc *crtc, struct drm_framebuffer *fb,

drivers/gpu/drm/i915/intel_drv.h

@@ -113,6 +113,7 @@ struct intel_fbdev {
 	struct intel_framebuffer *fb;
 	struct list_head fbdev_list;
 	struct drm_display_mode *our_mode;
+	int preferred_bpp;
 };
 
 struct intel_encoder {

drivers/gpu/drm/i915/intel_fbdev.c

@@ -128,6 +128,7 @@ static int intelfb_create(struct drm_fb_helper *helper,
 	struct drm_framebuffer *fb;
 	struct drm_i915_gem_object *obj;
 	int size, ret;
+	bool prealloc = false;
 
 	mutex_lock(&dev->struct_mutex);
 
@@ -139,6 +140,7 @@ static int intelfb_create(struct drm_fb_helper *helper,
 		intel_fb = ifbdev->fb;
 	} else {
 		DRM_DEBUG_KMS("re-using BIOS fb\n");
+		prealloc = true;
 		sizes->fb_width = intel_fb->base.width;
 		sizes->fb_height = intel_fb->base.height;
 	}
@@ -200,7 +202,7 @@ static int intelfb_create(struct drm_fb_helper *helper,
 	 * If the object is stolen however, it will be full of whatever
 	 * garbage was left in there.
 	 */
-	if (ifbdev->fb->obj->stolen)
+	if (ifbdev->fb->obj->stolen && !prealloc)
 		memset_io(info->screen_base, 0, info->screen_size);
 
 	/* Use default scratch pixmap (info->pixmap.flags = FB_PIXMAP_SYSTEM) */
@@ -454,27 +456,179 @@ static void intel_fbdev_destroy(struct drm_device *dev,
 	drm_framebuffer_remove(&ifbdev->fb->base);
 }
 
+/*
+ * Build an intel_fbdev struct using a BIOS allocated framebuffer, if possible.
+ * The core display code will have read out the current plane configuration,
+ * so we use that to figure out if there's an object for us to use as the
+ * fb, and if so, we re-use it for the fbdev configuration.
+ *
+ * Note we only support a single fb shared across pipes for boot (mostly for
+ * fbcon), so we just find the biggest and use that.
+ */
+static bool intel_fbdev_init_bios(struct drm_device *dev,
+				 struct intel_fbdev *ifbdev)
+{
+	struct intel_framebuffer *fb = NULL;
+	struct drm_crtc *crtc;
+	struct intel_crtc *intel_crtc;
+	struct intel_plane_config *plane_config = NULL;
+	unsigned int max_size = 0;
+
+	if (!i915.fastboot)
+		return false;
+
+	/* Find the largest fb */
+	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
+		intel_crtc = to_intel_crtc(crtc);
+
+		if (!intel_crtc->active || !intel_crtc->plane_config.fb) {
+			DRM_DEBUG_KMS("pipe %c not active or no fb, skipping\n",
+				      pipe_name(intel_crtc->pipe));
+			continue;
+		}
+
+		if (intel_crtc->plane_config.size > max_size) {
+			DRM_DEBUG_KMS("found possible fb from plane %c\n",
+				      pipe_name(intel_crtc->pipe));
+			plane_config = &intel_crtc->plane_config;
+			fb = plane_config->fb;
+			max_size = plane_config->size;
+		}
+	}
+
+	if (!fb) {
+		DRM_DEBUG_KMS("no active fbs found, not using BIOS config\n");
+		goto out;
+	}
+
+	/* Now make sure all the pipes will fit into it */
+	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
+		unsigned int cur_size;
+
+		intel_crtc = to_intel_crtc(crtc);
+
+		if (!intel_crtc->active) {
+			DRM_DEBUG_KMS("pipe %c not active, skipping\n",
+				      pipe_name(intel_crtc->pipe));
+			continue;
+		}
+
+		DRM_DEBUG_KMS("checking plane %c for BIOS fb\n",
+			      pipe_name(intel_crtc->pipe));
+
+		/*
+		 * See if the plane fb we found above will fit on this
+		 * pipe.  Note we need to use the selected fb's bpp rather
+		 * than the current pipe's, since they could be different.
+		 */
+		cur_size = intel_crtc->config.adjusted_mode.crtc_hdisplay *
+			intel_crtc->config.adjusted_mode.crtc_vdisplay;
+		DRM_DEBUG_KMS("pipe %c area: %d\n", pipe_name(intel_crtc->pipe),
+			      cur_size);
+		cur_size *= fb->base.bits_per_pixel / 8;
+		DRM_DEBUG_KMS("total size %d (bpp %d)\n", cur_size,
+			      fb->base.bits_per_pixel / 8);
+
+		if (cur_size > max_size) {
+			DRM_DEBUG_KMS("fb not big enough for plane %c (%d vs %d)\n",
+				      pipe_name(intel_crtc->pipe),
+				      cur_size, max_size);
+			plane_config = NULL;
+			fb = NULL;
+			break;
+		}
+
+		DRM_DEBUG_KMS("fb big enough for plane %c (%d >= %d)\n",
+			      pipe_name(intel_crtc->pipe),
+			      max_size, cur_size);
+	}
+
+	/* Free unused fbs */
+	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
+		struct intel_framebuffer *cur_fb;
+
+		intel_crtc = to_intel_crtc(crtc);
+		cur_fb = intel_crtc->plane_config.fb;
+
+		if (cur_fb && cur_fb != fb)
+			drm_framebuffer_unreference(&cur_fb->base);
+	}
+
+	if (!fb) {
+		DRM_DEBUG_KMS("BIOS fb not suitable for all pipes, not using\n");
+		goto out;
+	}
+
+	ifbdev->preferred_bpp = plane_config->fb->base.bits_per_pixel;
+	ifbdev->fb = fb;
+
+	/* Assuming a single fb across all pipes here */
+	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
+		intel_crtc = to_intel_crtc(crtc);
+
+		if (!intel_crtc->active)
+			continue;
+
+		/*
+		 * This should only fail on the first one so we don't need
+		 * to cleanup any secondary crtc->fbs
+		 */
+		if (intel_pin_and_fence_fb_obj(dev, fb->obj, NULL))
+			goto out_unref_obj;
+
+		crtc->fb = &fb->base;
+		drm_gem_object_reference(&fb->obj->base);
+		drm_framebuffer_reference(&fb->base);
+	}
+
+	/* Final pass to check if any active pipes don't have fbs */
+	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
+		intel_crtc = to_intel_crtc(crtc);
+
+		if (!intel_crtc->active)
+			continue;
+
+		WARN(!crtc->fb,
+		     "re-used BIOS config but lost an fb on crtc %d\n",
+		     crtc->base.id);
+	}
+
+
+	DRM_DEBUG_KMS("using BIOS fb for initial console\n");
+	return true;
+
+out_unref_obj:
+	drm_framebuffer_unreference(&fb->base);
+out:
+
+	return false;
+}
+
 int intel_fbdev_init(struct drm_device *dev)
 {
 	struct intel_fbdev *ifbdev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	int ret;
 
-	ifbdev = kzalloc(sizeof(*ifbdev), GFP_KERNEL);
-	if (!ifbdev)
+	if (WARN_ON(INTEL_INFO(dev)->num_pipes == 0))
+		return -ENODEV;
+
+	ifbdev = kzalloc(sizeof(struct intel_fbdev), GFP_KERNEL);
+	if (ifbdev == NULL)
 		return -ENOMEM;
 
-	dev_priv->fbdev = ifbdev;
 	ifbdev->helper.funcs = &intel_fb_helper_funcs;
+	if (!intel_fbdev_init_bios(dev, ifbdev))
+		ifbdev->preferred_bpp = 32;
 
 	ret = drm_fb_helper_init(dev, &ifbdev->helper,
-				 INTEL_INFO(dev)->num_pipes,
-				 4);
+				 INTEL_INFO(dev)->num_pipes, 4);
 	if (ret) {
 		kfree(ifbdev);
 		return ret;
 	}
 
+	dev_priv->fbdev = ifbdev;
 	drm_fb_helper_single_add_all_connectors(&ifbdev->helper);
 
 	return 0;
@@ -483,9 +637,10 @@ int intel_fbdev_init(struct drm_device *dev)
 void intel_fbdev_initial_config(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct intel_fbdev *ifbdev = dev_priv->fbdev;
 
 	/* Due to peculiar init order wrt to hpd handling this is separate. */
-	drm_fb_helper_initial_config(&dev_priv->fbdev->helper, 32);
+	drm_fb_helper_initial_config(&ifbdev->helper, ifbdev->preferred_bpp);
 }
 
 void intel_fbdev_fini(struct drm_device *dev)
@@ -523,7 +678,8 @@ void intel_fbdev_set_suspend(struct drm_device *dev, int state)
 void intel_fbdev_output_poll_changed(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	drm_fb_helper_hotplug_event(&dev_priv->fbdev->helper);
+	if (dev_priv->fbdev)
+		drm_fb_helper_hotplug_event(&dev_priv->fbdev->helper);
 }
 
 void intel_fbdev_restore_mode(struct drm_device *dev)
@@ -531,7 +687,7 @@ void intel_fbdev_restore_mode(struct drm_device *dev)
 	int ret;
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
-	if (INTEL_INFO(dev)->num_pipes == 0)
+	if (!dev_priv->fbdev)
 		return;
 
 	drm_modeset_lock_all(dev);