From: Mahesh Kumar <mahesh1.kumar@xxxxxxxxx>
This patch changes Watermak calculation to fixed point calculation.
Problem with current calculation is during plane_blocks_per_line
calculation we divide intermediate blocks with min_scanlines and
takes floor of the result because of integer operation.
hence we end-up assigning less blocks than required. Which leads to
flickers.
Signed-off-by: Mahesh Kumar <mahesh1.kumar@xxxxxxxxx>
---
drivers/gpu/drm/i915/intel_pm.c | 23 ++++++++++++++---------
1 file changed, 14 insertions(+), 9 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 0ec328b..d4390e4 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3530,13 +3530,15 @@ static uint32_t skl_pipe_pixel_rate(const struct intel_crtc_state *config)
*/
static uint32_t skl_wm_method1(uint32_t pixel_rate, uint8_t cpp, uint32_t latency)
{
- uint32_t wm_intermediate_val, ret;
+ uint64_t wm_intermediate_val;
+ uint32_t ret;
if (latency == 0)
return UINT_MAX;
- wm_intermediate_val = latency * pixel_rate * cpp / 512;
- ret = DIV_ROUND_UP(wm_intermediate_val, 1000);
+ wm_intermediate_val = latency * pixel_rate * cpp;
+ wm_intermediate_val <<= 16;
+ ret = DIV_ROUND_UP_ULL(wm_intermediate_val, 1000 * 512);
return ret;
}
@@ -3605,6 +3607,7 @@ static int skl_compute_plane_wm(const struct drm_i915_private *dev_priv,
uint16_t *out_blocks = &result->plane_res_b[id];
uint8_t *out_lines = &result->plane_res_l[id];
enum watermark_memory_wa mem_wa;
+ bool y_tiled = false;
if (latency == 0 || !cstate->base.active || !intel_pstate->base.visible)
return 0;
@@ -3652,14 +3655,18 @@ static int skl_compute_plane_wm(const struct drm_i915_private *dev_priv,
plane_bytes_per_line = width * cpp;
if (fb->modifier[0] == I915_FORMAT_MOD_Y_TILED ||
fb->modifier[0] == I915_FORMAT_MOD_Yf_TILED) {
+ y_tiled = true;
plane_blocks_per_line =
DIV_ROUND_UP(plane_bytes_per_line * y_min_scanlines, 512);
- plane_blocks_per_line /= y_min_scanlines;
+ plane_blocks_per_line = (plane_blocks_per_line << 16) /
+ y_min_scanlines;
} else if (fb->modifier[0] == DRM_FORMAT_MOD_NONE) {
plane_blocks_per_line = DIV_ROUND_UP(plane_bytes_per_line, 512)
+ 1;
+ plane_blocks_per_line <<= 16;
} else {
plane_blocks_per_line = DIV_ROUND_UP(plane_bytes_per_line, 512);
+ plane_blocks_per_line <<= 16;
}
method1 = skl_wm_method1(plane_pixel_rate, cpp, latency);
@@ -3670,8 +3677,7 @@ static int skl_compute_plane_wm(const struct drm_i915_private *dev_priv,
y_tile_minimum = plane_blocks_per_line * y_min_scanlines;
- if (fb->modifier[0] == I915_FORMAT_MOD_Y_TILED ||
- fb->modifier[0] == I915_FORMAT_MOD_Yf_TILED) {
+ if (y_tiled) {
selected_result = max(method2, y_tile_minimum);
} else {
uint32_t linetime_us = 0;
@@ -3688,12 +3694,11 @@ static int skl_compute_plane_wm(const struct drm_i915_private *dev_priv,
selected_result = method1;
}
- res_blocks = selected_result + 1;
+ res_blocks = DIV_ROUND_UP(selected_result, 1 << 16) + 1;
res_lines = DIV_ROUND_UP(selected_result, plane_blocks_per_line);
if (level >= 1 && level <= 7) {
- if (fb->modifier[0] == I915_FORMAT_MOD_Y_TILED ||
- fb->modifier[0] == I915_FORMAT_MOD_Yf_TILED) {
+ if (y_tiled) {
res_blocks += y_tile_minimum;
res_lines += y_min_scanlines;
} else {
--
2.8.3
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