[PATCH 04/10] drm/radeon: Handle 64-bit return from drm_crtc_vblank_count()

Dhinakaran Pandiyan dhinakaran.pandiyan at intel.com
Fri Feb 2 03:26:44 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/radeon/radeon_display.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c
index dfda5e0ed166..26129b2b082d 100644
--- a/drivers/gpu/drm/radeon/radeon_display.c
+++ b/drivers/gpu/drm/radeon/radeon_display.c
@@ -570,7 +570,7 @@ static int radeon_crtc_page_flip_target(struct drm_crtc *crtc,
 		base &= ~7;
 	work->base = base;
-	work->target_vblank = target - drm_crtc_vblank_count(crtc) +
+	work->target_vblank = target - (uint32_t)drm_crtc_vblank_count(crtc) +
 		dev->driver->get_vblank_counter(dev, work->crtc_id);
 	/* We borrow the event spin lock for protecting flip_work */

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