drm/radeon: Make display watermark calculations more accurate
Avoid big roundoff errors in scanline/hactive durations for
high pixel clocks, especially for >= 500 Mhz, and thereby
program more accurate display fifo watermarks.
This is a port of the corresponding amdgpu patch.
Implemented for DCE 4,6,8.
Tested on Evergreen/DCE-4 with Radeon HD-5770.
Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/radeon/evergreen.c b/drivers/gpu/drm/radeon/evergreen.c
index 3c9c133..f130ec4 100644
--- a/drivers/gpu/drm/radeon/evergreen.c
+++ b/drivers/gpu/drm/radeon/evergreen.c
@@ -2255,7 +2255,7 @@ static void evergreen_program_watermarks(struct radeon_device *rdev,
struct drm_display_mode *mode = &radeon_crtc->base.mode;
struct evergreen_wm_params wm_low, wm_high;
u32 dram_channels;
- u32 pixel_period;
+ u32 active_time;
u32 line_time = 0;
u32 latency_watermark_a = 0, latency_watermark_b = 0;
u32 priority_a_mark = 0, priority_b_mark = 0;
@@ -2266,8 +2266,8 @@ static void evergreen_program_watermarks(struct radeon_device *rdev,
fixed20_12 a, b, c;
if (radeon_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);
priority_a_cnt = 0;
priority_b_cnt = 0;
dram_channels = evergreen_get_number_of_dram_channels(rdev);
@@ -2285,7 +2285,7 @@ static void evergreen_program_watermarks(struct radeon_device *rdev,
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)
@@ -2312,7 +2312,7 @@ static void evergreen_program_watermarks(struct radeon_device *rdev,
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)