[PATCH 4.11 12/78] drm/amdgpu: Fix overflow of watermark calcs at > 4k resolutions.

Greg Kroah-Hartman
2017-06-19T15:16:54Z

From: Mario Kleiner <mario.kleiner.de@gmail.com>

commit bea10413934dcf98cb9b2dfcdc56e1d28f192897 upstream.

Commit d63c277dc672e0
("drm/amdgpu: Make display watermark calculations more accurate")
made watermark calculations more accurate, but not for > 4k
resolutions on 32-Bit architectures, as it introduced an integer
overflow for those setups and resolutions.

Fix this by proper u64 casting and division.

Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Reported-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Fixes: d63c277dc672 ("drm/amdgpu: Make display watermark calculations more accurate")
Cc: Ben Hutchings <ben.hutchings@codethink.co.uk>
Cc: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/gpu/drm/amd/amdgpu/dce_v10_0.c | 7 +++++--
drivers/gpu/drm/amd/amdgpu/dce_v11_0.c | 7 +++++--
drivers/gpu/drm/amd/amdgpu/dce_v6_0.c | 7 +++++--
drivers/gpu/drm/amd/amdgpu/dce_v8_0.c | 7 +++++--
4 files changed, 20 insertions(+), 8 deletions(-)

--- a/drivers/gpu/drm/amd/amdgpu/dce_v10_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/dce_v10_0.c
@@ -1207,8 +1207,11 @@ static void dce_v10_0_program_watermarks
u32 tmp, wm_mask, lb_vblank_lead_lines = 0;

if (amdgpu_crtc->base.enabled && num_heads && mode) {
- active_time = 1000000UL * (u32)mode->crtc_hdisplay / (u32)mode->clock;
- line_time = min((u32) (1000000UL * (u32)mode->crtc_htotal / (u32)mode->clock), (u32)65535);
+ active_time = (u32) div_u64((u64)mode->crtc_hdisplay * 1000000,
+ (u32)mode->clock);
+ line_time = (u32) div_u64((u64)mode->crtc_htotal * 1000000,
+ (u32)mode->clock);
+ line_time = min(line_time, (u32)65535);

/* watermark for high clocks */
if (adev->pm.dpm_enabled) {
--- a/drivers/gpu/drm/amd/amdgpu/dce_v11_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/dce_v11_0.c
@@ -1176,8 +1176,11 @@ static void dce_v11_0_program_watermarks
u32 tmp, wm_mask, lb_vblank_lead_lines = 0;

if (amdgpu_crtc->base.enabled && num_heads && mode) {
- active_time = 1000000UL * (u32)mode->crtc_hdisplay / (u32)mode->clock;
- line_time = min((u32) (1000000UL * (u32)mode->crtc_htotal / (u32)mode->clock), (u32)65535);
+ active_time = (u32) div_u64((u64)mode->crtc_hdisplay * 1000000,
+ (u32)mode->clock);
+ line_time = (u32) div_u64((u64)mode->crtc_htotal * 1000000,
+ (u32)mode->clock);
+ line_time = min(line_time, (u32)65535);

/* watermark for high clocks */
if (adev->pm.dpm_enabled) {
--- a/drivers/gpu/drm/amd/amdgpu/dce_v6_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/dce_v6_0.c
@@ -983,8 +983,11 @@ static void dce_v6_0_program_watermarks(
fixed20_12 a, b, c;

if (amdgpu_crtc->base.enabled && num_heads && mode) {
- active_time = 1000000UL * (u32)mode->crtc_hdisplay / (u32)mode->clock;
- line_time = min((u32) (1000000UL * (u32)mode->crtc_htotal / (u32)mode->clock), (u32)65535);
+ active_time = (u32) div_u64((u64)mode->crtc_hdisplay * 1000000,
+ (u32)mode->clock);
+ line_time = (u32) div_u64((u64)mode->crtc_htotal * 1000000,
+ (u32)mode->clock);
+ line_time = min(line_time, (u32)65535);
priority_a_cnt = 0;
priority_b_cnt = 0;

--- a/drivers/gpu/drm/amd/amdgpu/dce_v8_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/dce_v8_0.c
@@ -1091,8 +1091,11 @@ static void dce_v8_0_program_watermarks(
u32 tmp, wm_mask, lb_vblank_lead_lines = 0;

if (amdgpu_crtc->base.enabled && num_heads && mode) {
- active_time = 1000000UL * (u32)mode->crtc_hdisplay / (u32)mode->clock;
- line_time = min((u32) (1000000UL * (u32)mode->crtc_htotal / (u32)mode->clock), (u32)65535);
+ active_time = (u32) div_u64((u64)mode->crtc_hdisplay * 1000000,
+ (u32)mode->clock);
+ line_time = (u32) div_u64((u64)mode->crtc_htotal * 1000000,
+ (u32)mode->clock);
+ line_time = min(line_time, (u32)65535);

/* watermark for high clocks */
if (adev->pm.dpm_enabled) {