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drm: refcounting for crtc framebuffers 

With the prep patch to encapsulate ->set_crtc calls, this is now
rather easy. Hooray for inconsistent semantics between ->set_crtc and
->page_flip, where the driver callback is supposed to update the fb
pointer, and ->update_plane, where the drm core does the same.

Also, since the drm core functions check crtc->fb before calling into
driver callbacks, we can't really reduce the critical sections
protected by the mode_config locks.

Reviewed-by: Rob Clark <rob@ti.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Daniel Vetter 2012-12-11 01:07:12 +01:00
parent 6c2a75325c
commit b0d1232589
1 changed files with 30 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

37
drivers/gpu/drm/drm_crtc.c
View File

@ -1984,8 +1984,21 @@ out:
int drm_mode_set_config_internal(struct drm_mode_set *set)
{
struct drm_crtc *crtc = set->crtc;
struct drm_framebuffer *fb, *old_fb;
int ret;
return crtc->funcs->set_config(set);
old_fb = crtc->fb;
fb = set->fb;
ret = crtc->funcs->set_config(set);
if (ret == 0) {
if (old_fb)
drm_framebuffer_unreference(old_fb);
if (fb)
drm_framebuffer_reference(fb);
}
return ret;
}
EXPORT_SYMBOL(drm_mode_set_config_internal);
@ -2046,6 +2059,8 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data,
goto out;
}
fb = crtc->fb;
/* Make refcounting symmetric with the lookup path. */
drm_framebuffer_reference(fb);
} else {
fb = drm_framebuffer_lookup(dev, crtc_req->fb_id);
if (!fb) {
@ -2054,9 +2069,6 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data,
ret = -EINVAL;
goto out;
}
/* fb is protect by the mode_config lock, so drop the
* ref immediately */
drm_framebuffer_unreference(fb);
}
mode = drm_mode_create(dev);
@ -2156,6 +2168,9 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data,
ret = drm_mode_set_config_internal(&set);
out:
if (fb)
drm_framebuffer_unreference(fb);
kfree(connector_set);
drm_mode_destroy(dev, mode);
drm_modeset_unlock_all(dev);
@ -3656,7 +3671,7 @@ int drm_mode_page_flip_ioctl(struct drm_device *dev,
struct drm_mode_crtc_page_flip *page_flip = data;
struct drm_mode_object *obj;
struct drm_crtc *crtc;
struct drm_framebuffer *fb;
struct drm_framebuffer *fb = NULL, *old_fb = NULL;
struct drm_pending_vblank_event *e = NULL;
unsigned long flags;
int hdisplay, vdisplay;
@ -3687,8 +3702,6 @@ int drm_mode_page_flip_ioctl(struct drm_device *dev,
fb = drm_framebuffer_lookup(dev, page_flip->fb_id);
if (!fb)
goto out;
/* fb is protect by the mode_config lock, so drop the ref immediately */
drm_framebuffer_unreference(fb);
hdisplay = crtc->mode.hdisplay;
vdisplay = crtc->mode.vdisplay;
@ -3734,6 +3747,7 @@ int drm_mode_page_flip_ioctl(struct drm_device *dev,
(void (*) (struct drm_pending_event *)) kfree;
}
old_fb = crtc->fb;
ret = crtc->funcs->page_flip(crtc, fb, e);
if (ret) {
if (page_flip->flags & DRM_MODE_PAGE_FLIP_EVENT) {
@ -3742,9 +3756,18 @@ int drm_mode_page_flip_ioctl(struct drm_device *dev,
spin_unlock_irqrestore(&dev->event_lock, flags);
kfree(e);
}
/* Keep the old fb, don't unref it. */
old_fb = NULL;
} else {
/* Unref only the old framebuffer. */
fb = NULL;
}
out:
if (fb)
drm_framebuffer_unreference(fb);
if (old_fb)
drm_framebuffer_unreference(old_fb);
drm_modeset_unlock_all(dev);
return ret;
}