drm/atomic: Refcounting for plane_state->fb
So my original plan was that the drm core refcounts framebuffers like with the legacy ioctls. But that doesn't work for a bunch of reasons: - State objects might live longer than until the next fb change happens for a plane. For example delayed cleanup work only happens _after_ the pageflip ioctl has completed. So this definitely doesn't work without the plane state holding its own references. - The other issue is transition from legacy to atomic implementations, where the driver works under a mix of both worlds. Which means legacy paths might not properly update the ->fb pointer under plane->state->fb. Which is a bit a problem when then someone comes around and _does_ try to clean it up when it's long gone. The second issue is just a bit a transition bug, since drivers should update plane->state->fb in all the paths that aren't converted yet. But a bit more robustness for the transition can't hurt - we pull similar tricks with cleaning up the old fb in the transitional helpers already. The pattern for drivers that transition is if (plane->state) drm_atomic_set_fb_for_plane(plane->state, plane->fb); inserted after the fb update has logically completed at the end of ->set_config (or ->set_base/mode_set if using the crtc helpers), ->page_flip, ->update_plane or any other entry point which updates plane->fb. v2: Update kerneldoc - copypasta fail. v3: Fix spelling in the commit message (Sean). Reviewed-by: Sean Paul <seanpaul@chromium.org> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
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3150c7d0c6
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@ -367,6 +367,34 @@ drm_atomic_set_crtc_for_plane(struct drm_plane_state *plane_state,
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}
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EXPORT_SYMBOL(drm_atomic_set_crtc_for_plane);
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/**
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* drm_atomic_set_fb_for_plane - set crtc for plane
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* @plane_state: atomic state object for the plane
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* @fb: fb to use for the plane
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*
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* Changing the assigned framebuffer for a plane requires us to grab a reference
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* to the new fb and drop the reference to the old fb, if there is one. This
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* function takes care of all these details besides updating the pointer in the
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* state object itself.
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*/
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void
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drm_atomic_set_fb_for_plane(struct drm_plane_state *plane_state,
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struct drm_framebuffer *fb)
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{
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if (plane_state->fb)
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drm_framebuffer_unreference(plane_state->fb);
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if (fb)
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drm_framebuffer_reference(fb);
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plane_state->fb = fb;
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if (fb)
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DRM_DEBUG_KMS("Set [FB:%d] for plane state %p\n",
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fb->base.id, plane_state);
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else
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DRM_DEBUG_KMS("Set [NOFB] for plane state %p\n", plane_state);
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}
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EXPORT_SYMBOL(drm_atomic_set_fb_for_plane);
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/**
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* drm_atomic_set_crtc_for_connector - set crtc for connector
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* @conn_state: atomic state object for the connector
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@ -1182,7 +1182,7 @@ retry:
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ret = drm_atomic_set_crtc_for_plane(plane_state, crtc);
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if (ret != 0)
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goto fail;
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plane_state->fb = fb;
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drm_atomic_set_fb_for_plane(plane_state, fb);
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plane_state->crtc_x = crtc_x;
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plane_state->crtc_y = crtc_y;
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plane_state->crtc_h = crtc_h;
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@ -1250,7 +1250,7 @@ retry:
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ret = drm_atomic_set_crtc_for_plane(plane_state, NULL);
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if (ret != 0)
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goto fail;
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plane_state->fb = NULL;
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drm_atomic_set_fb_for_plane(plane_state, NULL);
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plane_state->crtc_x = 0;
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plane_state->crtc_y = 0;
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plane_state->crtc_h = 0;
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@ -1422,7 +1422,7 @@ retry:
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ret = drm_atomic_set_crtc_for_plane(primary_state, crtc);
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if (ret != 0)
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goto fail;
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primary_state->fb = set->fb;
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drm_atomic_set_fb_for_plane(primary_state, set->fb);
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primary_state->crtc_x = 0;
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primary_state->crtc_y = 0;
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primary_state->crtc_h = set->mode->vdisplay;
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@ -1694,7 +1694,7 @@ retry:
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ret = drm_atomic_set_crtc_for_plane(plane_state, crtc);
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if (ret != 0)
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goto fail;
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plane_state->fb = fb;
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drm_atomic_set_fb_for_plane(plane_state, fb);
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ret = drm_atomic_async_commit(state);
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if (ret != 0)
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@ -1808,6 +1808,9 @@ EXPORT_SYMBOL(drm_atomic_helper_crtc_destroy_state);
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*/
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void drm_atomic_helper_plane_reset(struct drm_plane *plane)
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{
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if (plane->state && plane->state->fb)
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drm_framebuffer_unreference(plane->state->fb);
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kfree(plane->state);
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plane->state = kzalloc(sizeof(*plane->state), GFP_KERNEL);
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}
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@ -1823,10 +1826,17 @@ EXPORT_SYMBOL(drm_atomic_helper_plane_reset);
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struct drm_plane_state *
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drm_atomic_helper_plane_duplicate_state(struct drm_plane *plane)
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{
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struct drm_plane_state *state;
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if (WARN_ON(!plane->state))
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return NULL;
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return kmemdup(plane->state, sizeof(*plane->state), GFP_KERNEL);
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state = kmemdup(plane->state, sizeof(*plane->state), GFP_KERNEL);
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if (state && state->fb)
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drm_framebuffer_reference(state->fb);
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return state;
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}
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EXPORT_SYMBOL(drm_atomic_helper_plane_duplicate_state);
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@ -1839,8 +1849,11 @@ EXPORT_SYMBOL(drm_atomic_helper_plane_duplicate_state);
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* subclassed plane state structure.
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*/
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void drm_atomic_helper_plane_destroy_state(struct drm_plane *plane,
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struct drm_plane_state *state)
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struct drm_plane_state *state)
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{
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if (state->fb)
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drm_framebuffer_unreference(state->fb);
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kfree(state);
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}
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EXPORT_SYMBOL(drm_atomic_helper_plane_destroy_state);
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@ -34,11 +34,13 @@
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#include <linux/moduleparam.h>
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#include <drm/drmP.h>
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#include <drm/drm_atomic.h>
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#include <drm/drm_crtc.h>
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#include <drm/drm_fourcc.h>
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#include <drm/drm_crtc_helper.h>
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#include <drm/drm_fb_helper.h>
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#include <drm/drm_plane_helper.h>
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#include <drm/drm_atomic_helper.h>
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#include <drm/drm_edid.h>
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/**
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@ -998,15 +1000,14 @@ int drm_helper_crtc_mode_set_base(struct drm_crtc *crtc, int x, int y,
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if (plane->funcs->atomic_duplicate_state)
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plane_state = plane->funcs->atomic_duplicate_state(plane);
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else if (plane->state)
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plane_state = kmemdup(plane->state, sizeof(*plane_state),
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GFP_KERNEL);
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plane_state = drm_atomic_helper_plane_duplicate_state(plane);
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else
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plane_state = kzalloc(sizeof(*plane_state), GFP_KERNEL);
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if (!plane_state)
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return -ENOMEM;
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plane_state->crtc = crtc;
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plane_state->fb = crtc->primary->fb;
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drm_atomic_set_fb_for_plane(plane_state, crtc->primary->fb);
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plane_state->crtc_x = 0;
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plane_state->crtc_y = 0;
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plane_state->crtc_h = crtc->mode.vdisplay;
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@ -27,7 +27,9 @@
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#include <drm/drmP.h>
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#include <drm/drm_plane_helper.h>
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#include <drm/drm_rect.h>
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#include <drm/drm_atomic.h>
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#include <drm/drm_crtc_helper.h>
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#include <drm/drm_atomic_helper.h>
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#define SUBPIXEL_MASK 0xffff
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@ -464,7 +466,7 @@ out:
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if (plane->funcs->atomic_destroy_state)
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plane->funcs->atomic_destroy_state(plane, plane_state);
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else
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kfree(plane_state);
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drm_atomic_helper_plane_destroy_state(plane, plane_state);
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}
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return ret;
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@ -505,15 +507,14 @@ int drm_plane_helper_update(struct drm_plane *plane, struct drm_crtc *crtc,
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if (plane->funcs->atomic_duplicate_state)
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plane_state = plane->funcs->atomic_duplicate_state(plane);
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else if (plane->state)
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plane_state = kmemdup(plane->state, sizeof(*plane_state),
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GFP_KERNEL);
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plane_state = drm_atomic_helper_plane_duplicate_state(plane);
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else
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plane_state = kzalloc(sizeof(*plane_state), GFP_KERNEL);
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if (!plane_state)
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return -ENOMEM;
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plane_state->crtc = crtc;
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plane_state->fb = fb;
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drm_atomic_set_fb_for_plane(plane_state, fb);
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plane_state->crtc_x = crtc_x;
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plane_state->crtc_y = crtc_y;
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plane_state->crtc_h = crtc_h;
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@ -552,15 +553,14 @@ int drm_plane_helper_disable(struct drm_plane *plane)
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if (plane->funcs->atomic_duplicate_state)
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plane_state = plane->funcs->atomic_duplicate_state(plane);
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else if (plane->state)
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plane_state = kmemdup(plane->state, sizeof(*plane_state),
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GFP_KERNEL);
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plane_state = drm_atomic_helper_plane_duplicate_state(plane);
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else
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plane_state = kzalloc(sizeof(*plane_state), GFP_KERNEL);
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if (!plane_state)
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return -ENOMEM;
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plane_state->crtc = NULL;
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plane_state->fb = NULL;
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drm_atomic_set_fb_for_plane(plane_state, NULL);
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return drm_plane_helper_commit(plane, plane_state, plane->fb);
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}
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@ -46,6 +46,8 @@ drm_atomic_get_connector_state(struct drm_atomic_state *state,
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int __must_check
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drm_atomic_set_crtc_for_plane(struct drm_plane_state *plane_state,
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struct drm_crtc *crtc);
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void drm_atomic_set_fb_for_plane(struct drm_plane_state *plane_state,
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struct drm_framebuffer *fb);
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int __must_check
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drm_atomic_set_crtc_for_connector(struct drm_connector_state *conn_state,
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struct drm_crtc *crtc);
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