[Intel-gfx] [PATCH v2 2/2] drm/i915: Tear down fbdev if initialization fails

[Lukas Wunner]

Currently if intelfb_create() errors out, it unrefs the bo even though
the fb now owns that reference. (Spotted by Ville Syrjälä.) We should
unref the fb instead of the bo.

However the fb was not necessarily allocated by intelfb_create(),
it could be inherited from BIOS (the fb struct was then allocated by
dev_priv->display.get_initial_plane_config()) and be in active use by
a crtc. In this case we should call drm_framebuffer_remove() instead
of _unreference() to also disable the crtc.

Daniel Vetter suggested that "fbdev teardown code will take care of it.
The correct approach is probably to not unref anything at all".

But if fbdev initialization fails, the fbdev isn't torn down and
occupies memory even though it's unusable. Therefore clobber it in
intel_fbdev_initial_config(). (Currently we ignore a negative return
value there.) The idea is that if fbdev initialization fails, the driver
behaves as if CONFIG_DRM_FBDEV_EMULATION wasn't set.

Also, log errors in intelfb_create().

Move async_synchronize_full() from intel_fbdev_fini() to its sole caller
i915_driver_unload() to avoid deadlock if fbdev initialization fails.

v2: Instead of calling drm_framebuffer_unreference() (if fb was not
    inherited from BIOS), call intel_fbdev_fini().

Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Signed-off-by: Lukas Wunner <lukas at wunner.de>
---
 drivers/gpu/drm/i915/i915_dma.c    | 1 +
 drivers/gpu/drm/i915/intel_fbdev.c | 9 +++++----
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index ffcb9c6..68ab51d 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -1154,6 +1154,7 @@ int i915_driver_unload(struct drm_device *dev)
 
 	acpi_video_unregister();
 
+	async_synchronize_full();
 	intel_fbdev_fini(dev);
 
 	drm_vblank_cleanup(dev);
diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
index 05484ba..2969447 100644
--- a/drivers/gpu/drm/i915/intel_fbdev.c
+++ b/drivers/gpu/drm/i915/intel_fbdev.c
@@ -227,6 +227,7 @@ static int intelfb_create(struct drm_fb_helper *helper,
 
 	info = drm_fb_helper_alloc_fbi(helper);
 	if (IS_ERR(info)) {
+		DRM_ERROR("Failed to allocate fb_info\n");
 		ret = PTR_ERR(info);
 		goto out_unpin;
 	}
@@ -253,6 +254,7 @@ static int intelfb_create(struct drm_fb_helper *helper,
 		ioremap_wc(dev_priv->gtt.mappable_base + i915_gem_obj_ggtt_offset(obj),
 			   size);
 	if (!info->screen_base) {
+		DRM_ERROR("Failed to remap framebuffer into virtual memory\n");
 		ret = -ENOSPC;
 		goto out_destroy_fbi;
 	}
@@ -285,7 +287,6 @@ out_destroy_fbi:
 	drm_fb_helper_release_fbi(helper);
 out_unpin:
 	i915_gem_object_ggtt_unpin(obj);
-	drm_gem_object_unreference(&obj->base);
 	mutex_unlock(&dev->struct_mutex);
 	return ret;
 }
@@ -713,7 +714,9 @@ void intel_fbdev_initial_config(void *data, async_cookie_t cookie)
 	struct intel_fbdev *ifbdev = dev_priv->fbdev;
 
 	/* Due to peculiar init order wrt to hpd handling this is separate. */
-	drm_fb_helper_initial_config(&ifbdev->helper, ifbdev->preferred_bpp);
+	if (drm_fb_helper_initial_config(&ifbdev->helper,
+					 ifbdev->preferred_bpp))
+		intel_fbdev_fini(dev_priv->dev);
 }
 
 void intel_fbdev_fini(struct drm_device *dev)
@@ -723,8 +726,6 @@ void intel_fbdev_fini(struct drm_device *dev)
 		return;
 
 	flush_work(&dev_priv->fbdev_suspend_work);
-
-	async_synchronize_full();
 	intel_fbdev_destroy(dev, dev_priv->fbdev);
 	kfree(dev_priv->fbdev);
 	dev_priv->fbdev = NULL;
-- 
1.8.5.2 (Apple Git-48)