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/cik.c b/drivers/gpu/drm/radeon/cik.c
index 4f034cb..ccebe0f 100644 (file)
--- a/drivers/gpu/drm/radeon/cik.c
+++ b/drivers/gpu/drm/radeon/cik.c
@@ -9261,14 +9261,14 @@ static void dce8_program_watermarks(struct radeon_device *rdev,
 {
        struct drm_display_mode *mode = &radeon_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;
 
        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);
 
                /* watermark for high clocks */
                if ((rdev->pm.pm_method == PM_METHOD_DPM) &&
@@ -9284,7 +9284,7 @@ static void dce8_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)
@@ -9324,7 +9324,7 @@ static void dce8_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)

diff --git a/drivers/gpu/drm/radeon/evergreen.c b/drivers/gpu/drm/radeon/evergreen.c
index 3c9c133..f130ec4 100644 (file)
--- 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)

diff --git a/drivers/gpu/drm/radeon/si.c b/drivers/gpu/drm/radeon/si.c
index 3efdfd0..ceee87f 100644 (file)
--- a/drivers/gpu/drm/radeon/si.c
+++ b/drivers/gpu/drm/radeon/si.c
@@ -2274,7 +2274,7 @@ static void dce6_program_watermarks(struct radeon_device *rdev,
        struct drm_display_mode *mode = &radeon_crtc->base.mode;
        struct dce6_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;
@@ -2284,8 +2284,8 @@ static void dce6_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;
 
@@ -2307,7 +2307,7 @@ static void dce6_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)
@@ -2334,7 +2334,7 @@ static void dce6_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)