[PATCH 05/10] drm/radeon: Handle 64-bit return from drm_crtc_vblank_count()

Dhinakaran Pandiyan
2018-02-03T05:12:57Z

570e86963a51 ("drm: Widen vblank count to 64-bits [v3]") changed the
return type for drm_crtc_vblank_count() to u64. This could cause
potential problems if the return value is used in arithmetic operations
with a 32-bit reference HW vblank count. Explicitly typecasting this down
to u32 either fixes a potential problem or serves to add clarity in case
the implicit typecasting was already correct.

Cc: Keith Packard <keithp@keithp.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@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 */
--
2.14.1