4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

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

commit d63c277dc672e0c568481af043359420fa9d4736 upstream.

Avoid big roundoff errors in scanline/hactive durations for
high pixel clocks, especially for >= 500 Mhz, and thereby
program more accurate display fifo watermarks.

Implemented here for DCE 6,8,10,11.
Successfully tested on DCE 10 with AMD R9 380 Tonga.

Reviewed-by: Alex Deucher <alexander.deuc...@amd.com>
Signed-off-by: Mario Kleiner <mario.kleiner...@gmail.com>
Signed-off-by: Alex Deucher <alexander.deuc...@amd.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/gpu/drm/amd/amdgpu/dce_v10_0.c |   10 +++++-----
 drivers/gpu/drm/amd/amdgpu/dce_v11_0.c |   10 +++++-----
 drivers/gpu/drm/amd/amdgpu/dce_v8_0.c  |   10 +++++-----
 3 files changed, 15 insertions(+), 15 deletions(-)

--- a/drivers/gpu/drm/amd/amdgpu/dce_v10_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/dce_v10_0.c
@@ -1237,14 +1237,14 @@ static void dce_v10_0_program_watermarks
 {
        struct drm_display_mode *mode = &amdgpu_crtc->base.mode;
        struct dce10_wm_params wm_low, wm_high;
-       u32 pixel_period;
+       u32 active_time;
        u32 line_time = 0;
        u32 latency_watermark_a = 0, latency_watermark_b = 0;
        u32 tmp, wm_mask, lb_vblank_lead_lines = 0;
 
        if (amdgpu_crtc->base.enabled && num_heads && mode) {
-               pixel_period = 1000000 / (u32)mode->clock;
-               line_time = min((u32)mode->crtc_htotal * pixel_period, 
(u32)65535);
+               active_time = 1000000UL * (u32)mode->crtc_hdisplay / 
(u32)mode->clock;
+               line_time = min((u32) (1000000UL * (u32)mode->crtc_htotal / 
(u32)mode->clock), (u32)65535);
 
                /* watermark for high clocks */
                if (adev->pm.dpm_enabled) {
@@ -1259,7 +1259,7 @@ static void dce_v10_0_program_watermarks
 
                wm_high.disp_clk = mode->clock;
                wm_high.src_width = mode->crtc_hdisplay;
-               wm_high.active_time = mode->crtc_hdisplay * pixel_period;
+               wm_high.active_time = active_time;
                wm_high.blank_time = line_time - wm_high.active_time;
                wm_high.interlaced = false;
                if (mode->flags & DRM_MODE_FLAG_INTERLACE)
@@ -1298,7 +1298,7 @@ static void dce_v10_0_program_watermarks
 
                wm_low.disp_clk = mode->clock;
                wm_low.src_width = mode->crtc_hdisplay;
-               wm_low.active_time = mode->crtc_hdisplay * pixel_period;
+               wm_low.active_time = active_time;
                wm_low.blank_time = line_time - wm_low.active_time;
                wm_low.interlaced = false;
                if (mode->flags & DRM_MODE_FLAG_INTERLACE)
--- a/drivers/gpu/drm/amd/amdgpu/dce_v11_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/dce_v11_0.c
@@ -1225,14 +1225,14 @@ static void dce_v11_0_program_watermarks
 {
        struct drm_display_mode *mode = &amdgpu_crtc->base.mode;
        struct dce10_wm_params wm_low, wm_high;
-       u32 pixel_period;
+       u32 active_time;
        u32 line_time = 0;
        u32 latency_watermark_a = 0, latency_watermark_b = 0;
        u32 tmp, wm_mask, lb_vblank_lead_lines = 0;
 
        if (amdgpu_crtc->base.enabled && num_heads && mode) {
-               pixel_period = 1000000 / (u32)mode->clock;
-               line_time = min((u32)mode->crtc_htotal * pixel_period, 
(u32)65535);
+               active_time = 1000000UL * (u32)mode->crtc_hdisplay / 
(u32)mode->clock;
+               line_time = min((u32) (1000000UL * (u32)mode->crtc_htotal / 
(u32)mode->clock), (u32)65535);
 
                /* watermark for high clocks */
                if (adev->pm.dpm_enabled) {
@@ -1247,7 +1247,7 @@ static void dce_v11_0_program_watermarks
 
                wm_high.disp_clk = mode->clock;
                wm_high.src_width = mode->crtc_hdisplay;
-               wm_high.active_time = mode->crtc_hdisplay * pixel_period;
+               wm_high.active_time = active_time;
                wm_high.blank_time = line_time - wm_high.active_time;
                wm_high.interlaced = false;
                if (mode->flags & DRM_MODE_FLAG_INTERLACE)
@@ -1286,7 +1286,7 @@ static void dce_v11_0_program_watermarks
 
                wm_low.disp_clk = mode->clock;
                wm_low.src_width = mode->crtc_hdisplay;
-               wm_low.active_time = mode->crtc_hdisplay * pixel_period;
+               wm_low.active_time = active_time;
                wm_low.blank_time = line_time - wm_low.active_time;
                wm_low.interlaced = false;
                if (mode->flags & DRM_MODE_FLAG_INTERLACE)
--- a/drivers/gpu/drm/amd/amdgpu/dce_v8_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/dce_v8_0.c
@@ -1207,14 +1207,14 @@ static void dce_v8_0_program_watermarks(
 {
        struct drm_display_mode *mode = &amdgpu_crtc->base.mode;
        struct dce8_wm_params wm_low, wm_high;
-       u32 pixel_period;
+       u32 active_time;
        u32 line_time = 0;
        u32 latency_watermark_a = 0, latency_watermark_b = 0;
        u32 tmp, wm_mask, lb_vblank_lead_lines = 0;
 
        if (amdgpu_crtc->base.enabled && num_heads && mode) {
-               pixel_period = 1000000 / (u32)mode->clock;
-               line_time = min((u32)mode->crtc_htotal * pixel_period, 
(u32)65535);
+               active_time = 1000000UL * (u32)mode->crtc_hdisplay / 
(u32)mode->clock;
+               line_time = min((u32) (1000000UL * (u32)mode->crtc_htotal / 
(u32)mode->clock), (u32)65535);
 
                /* watermark for high clocks */
                if (adev->pm.dpm_enabled) {
@@ -1229,7 +1229,7 @@ static void dce_v8_0_program_watermarks(
 
                wm_high.disp_clk = mode->clock;
                wm_high.src_width = mode->crtc_hdisplay;
-               wm_high.active_time = mode->crtc_hdisplay * pixel_period;
+               wm_high.active_time = active_time;
                wm_high.blank_time = line_time - wm_high.active_time;
                wm_high.interlaced = false;
                if (mode->flags & DRM_MODE_FLAG_INTERLACE)
@@ -1268,7 +1268,7 @@ static void dce_v8_0_program_watermarks(
 
                wm_low.disp_clk = mode->clock;
                wm_low.src_width = mode->crtc_hdisplay;
-               wm_low.active_time = mode->crtc_hdisplay * pixel_period;
+               wm_low.active_time = active_time;
                wm_low.blank_time = line_time - wm_low.active_time;
                wm_low.interlaced = false;
                if (mode->flags & DRM_MODE_FLAG_INTERLACE)


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