xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

drm: refcnt drm_framebuffer (v4.1)

Browse Source 
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>
This commit is contained in:
Rob Clark
2012-09-05 21:48:38 +00:00
committed by Dave Airlie
parent 33cce6e980
commit f7eff60ea0
4 changed files with 85 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
include/drm/drm_crtc.h
View File

@@ -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);