[PATCH 03/10] drm/amdgpu: Handle 64-bit return from drm_crtc_vblank_count()

Dhinakaran Pandiyan dhinakaran.pandiyan at intel.com
Fri Feb 2 03:26:43 UTC 2018


570e86963a51 ("drm: Widen vblank count to 64-bits [v3]") changed the
return type for drm_crtc_vblank_count() to u64. This could cause
problems if the return from the function is directly compared against
a 32-bit reference vblank count. Explicitly typecasting this down to
u32 either fixes a potential problem or serves as documentation in case
the typecasting was implicitly done.

Cc: Keith Packard <keithp at keithp.com>
Cc: Alex Deucher <alexander.deucher at amd.com>
Cc: Harry Wentland <harry.wentland at amd.com>
Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_display.c       | 2 +-
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
index 38d47559f098..c2fa5d55f04e 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
@@ -207,7 +207,7 @@ int amdgpu_crtc_page_flip_target(struct drm_crtc *crtc,
 	amdgpu_bo_unreserve(new_abo);
 
 	work->base = base;
-	work->target_vblank = target - drm_crtc_vblank_count(crtc) +
+	work->target_vblank = target - (uint32_t)drm_crtc_vblank_count(crtc) +
 		amdgpu_get_vblank_counter_kms(dev, work->crtc_id);
 
 	/* we borrow the event spin lock for protecting flip_wrok */
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 1ce4c98385e3..b7254a29b34a 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -3836,7 +3836,7 @@ static void amdgpu_dm_do_flip(struct drm_crtc *crtc,
 
 
 	/* Prepare wait for target vblank early - before the fence-waits */
-	target_vblank = target - drm_crtc_vblank_count(crtc) +
+	target_vblank = target - (uint32_t)drm_crtc_vblank_count(crtc) +
 			amdgpu_get_vblank_counter_kms(crtc->dev, acrtc->crtc_id);
 
 	/* TODO This might fail and hence better not used, wait
@@ -3982,7 +3982,7 @@ static void amdgpu_dm_commit_planes(struct drm_atomic_state *state,
 			amdgpu_dm_do_flip(
 				crtc,
 				fb,
-				drm_crtc_vblank_count(crtc) + *wait_for_vblank,
+				(uint32_t)drm_crtc_vblank_count(crtc) + *wait_for_vblank,
 				dm_state->context);
 		}
 
-- 
2.14.1



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