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authorRob Clark <rob@ti.com>2012-09-05 21:48:38 +0000
committerDave Airlie <airlied@redhat.com>2012-10-02 22:15:39 +1000
commitf7eff60ea0e4e35732604e3591e2ff7b3ef41981 (patch)
treea9dd6031479ce9585d7d0af061aa165ed9c5d49b /include
parent33cce6e9801f7d0184a636e9096a7cf7f8237ff9 (diff)
downloadlinux-f7eff60ea0e4e35732604e3591e2ff7b3ef41981.tar.bz2
drm: refcnt drm_framebuffer (v4.1)
This simplifies drm fb lifetime, and if the crtc/plane needs to hold a ref to the fb when disabling a pipe until the next vblank, this avoids the need to make disabling an overlay synchronous. This is a problem that shows up when userspace is using a drm plane to implement a hw cursor.. making overlay disable synchronous causes a performance problem when x11 is rapidly enabling/disabling the hw cursor. But not making it synchronous opens up a race condition for crashing if userspace turns around and immediately deletes the fb. Refcnt'ing the fb makes it possible to solve this problem. v1: original v2: add drm_framebuffer_remove() which is called in all paths where fb->funcs->destroy() was directly called before. This cleans up the CRTCs/planes that the fb was attached to. You should only directly use drm_framebuffer_unreference() if you are also using drm_framebuffer_reference() to keep a ref to the fb. v3: add comment explaining the fb refcount v4: remove duplicate 'list_del(&fb->filp_head)' [airlied: v4.1: fix local rejection] Signed-off-by: Rob Clark <rob@ti.com> Signed-off-by: Dave Airlie <airlied@redhat.com>
Diffstat (limited to 'include')
-rw-r--r--include/drm/drm_crtc.h14
1 files changed, 14 insertions, 0 deletions
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index eb91d520ce0b..68fdb299e39f 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -218,6 +218,7 @@ struct drm_display_info {
};
struct drm_framebuffer_funcs {
+ /* note: use drm_framebuffer_remove() */
void (*destroy)(struct drm_framebuffer *framebuffer);
int (*create_handle)(struct drm_framebuffer *fb,
struct drm_file *file_priv,
@@ -242,6 +243,16 @@ struct drm_framebuffer_funcs {
struct drm_framebuffer {
struct drm_device *dev;
+ /*
+ * Note that the fb is refcounted for the benefit of driver internals,
+ * for example some hw, disabling a CRTC/plane is asynchronous, and
+ * scanout does not actually complete until the next vblank. So some
+ * cleanup (like releasing the reference(s) on the backing GEM bo(s))
+ * should be deferred. In cases like this, the driver would like to
+ * hold a ref to the fb even though it has already been removed from
+ * userspace perspective.
+ */
+ struct kref refcount;
struct list_head head;
struct drm_mode_object base;
const struct drm_framebuffer_funcs *funcs;
@@ -919,6 +930,9 @@ extern void drm_framebuffer_set_object(struct drm_device *dev,
extern int drm_framebuffer_init(struct drm_device *dev,
struct drm_framebuffer *fb,
const struct drm_framebuffer_funcs *funcs);
+extern void drm_framebuffer_unreference(struct drm_framebuffer *fb);
+extern void drm_framebuffer_reference(struct drm_framebuffer *fb);
+extern void drm_framebuffer_remove(struct drm_framebuffer *fb);
extern void drm_framebuffer_cleanup(struct drm_framebuffer *fb);
extern int drmfb_probe(struct drm_device *dev, struct drm_crtc *crtc);
extern int drmfb_remove(struct drm_device *dev, struct drm_framebuffer *fb);