drm/i915/skl+: change WM calc to fixed point 16.16
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.
Changes since V1:
- Add fixed point data type as per Paulo's review
Changes since V2:
- use fixed_point instead of fp_16_16
Changes since V3:
- rebase
Changes since V4 (from Paulo):
- My original renaming suggestion was misunderstood, so implement it
- Simplify fixed_16_16_to_u32 implementation
- Fix indentation
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Mahesh Kumar <mahesh1.kumar@intel.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161201154940.24446-6-mahesh1.kumar@intel.com
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 315a1b3..9171431 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3509,32 +3509,35 @@ skl_allocate_pipe_ddb(struct intel_crtc_state *cstate,
* should allow pixel_rate up to ~2 GHz which seems sufficient since max
* 2xcdclk is 1350 MHz and the pixel rate should never exceed that.
*/
-static uint32_t skl_wm_method1(uint32_t pixel_rate, uint8_t cpp, uint32_t latency)
+static uint_fixed_16_16_t skl_wm_method1(uint32_t pixel_rate, uint8_t cpp,
+ uint32_t latency)
{
- uint32_t wm_intermediate_val, ret;
+ uint32_t wm_intermediate_val;
+ uint_fixed_16_16_t ret;
if (latency == 0)
- return UINT_MAX;
+ return FP_16_16_MAX;
- wm_intermediate_val = latency * pixel_rate * cpp / 512;
- ret = DIV_ROUND_UP(wm_intermediate_val, 1000);
-
+ wm_intermediate_val = latency * pixel_rate * cpp;
+ ret = fixed_16_16_div_round_up_u64(wm_intermediate_val, 1000 * 512);
return ret;
}
-static uint32_t skl_wm_method2(uint32_t pixel_rate, uint32_t pipe_htotal,
- uint32_t latency, uint32_t plane_blocks_per_line)
+static uint_fixed_16_16_t skl_wm_method2(uint32_t pixel_rate,
+ uint32_t pipe_htotal,
+ uint32_t latency,
+ uint_fixed_16_16_t plane_blocks_per_line)
{
- uint32_t ret;
uint32_t wm_intermediate_val;
+ uint_fixed_16_16_t ret;
if (latency == 0)
- return UINT_MAX;
+ return FP_16_16_MAX;
wm_intermediate_val = latency * pixel_rate;
- ret = DIV_ROUND_UP(wm_intermediate_val, pipe_htotal * 1000) *
- plane_blocks_per_line;
-
+ wm_intermediate_val = DIV_ROUND_UP(wm_intermediate_val,
+ pipe_htotal * 1000);
+ ret = mul_u32_fixed_16_16(wm_intermediate_val, plane_blocks_per_line);
return ret;
}
@@ -3574,14 +3577,17 @@ static int skl_compute_plane_wm(const struct drm_i915_private *dev_priv,
struct drm_plane_state *pstate = &intel_pstate->base;
struct drm_framebuffer *fb = pstate->fb;
uint32_t latency = dev_priv->wm.skl_latency[level];
- uint32_t method1, method2;
- uint32_t plane_bytes_per_line, plane_blocks_per_line;
+ uint_fixed_16_16_t method1, method2;
+ uint_fixed_16_16_t plane_blocks_per_line;
+ uint_fixed_16_16_t selected_result;
+ uint32_t interm_pbpl;
+ uint32_t plane_bytes_per_line;
uint32_t res_blocks, res_lines;
- uint32_t selected_result;
uint8_t cpp;
uint32_t width = 0, height = 0;
uint32_t plane_pixel_rate;
- uint32_t y_tile_minimum, y_min_scanlines;
+ uint_fixed_16_16_t y_tile_minimum;
+ uint32_t y_min_scanlines;
struct intel_atomic_state *state =
to_intel_atomic_state(cstate->base.state);
bool apply_memory_bw_wa = skl_needs_memory_bw_wa(state);
@@ -3640,14 +3646,16 @@ static int skl_compute_plane_wm(const struct drm_i915_private *dev_priv,
plane_bytes_per_line = width * cpp;
if (y_tiled) {
+ interm_pbpl = DIV_ROUND_UP(plane_bytes_per_line *
+ y_min_scanlines, 512);
plane_blocks_per_line =
- DIV_ROUND_UP(plane_bytes_per_line * y_min_scanlines, 512);
- plane_blocks_per_line /= y_min_scanlines;
+ fixed_16_16_div_round_up(interm_pbpl, y_min_scanlines);
} else if (x_tiled) {
- plane_blocks_per_line = DIV_ROUND_UP(plane_bytes_per_line, 512);
+ interm_pbpl = DIV_ROUND_UP(plane_bytes_per_line, 512);
+ plane_blocks_per_line = u32_to_fixed_16_16(interm_pbpl);
} else {
- plane_blocks_per_line = DIV_ROUND_UP(plane_bytes_per_line, 512)
- + 1;
+ interm_pbpl = DIV_ROUND_UP(plane_bytes_per_line, 512) + 1;
+ plane_blocks_per_line = u32_to_fixed_16_16(interm_pbpl);
}
method1 = skl_wm_method1(plane_pixel_rate, cpp, latency);
@@ -3656,26 +3664,29 @@ static int skl_compute_plane_wm(const struct drm_i915_private *dev_priv,
latency,
plane_blocks_per_line);
- y_tile_minimum = plane_blocks_per_line * y_min_scanlines;
+ y_tile_minimum = mul_u32_fixed_16_16(y_min_scanlines,
+ plane_blocks_per_line);
if (y_tiled) {
- selected_result = max(method2, y_tile_minimum);
+ selected_result = max_fixed_16_16(method2, y_tile_minimum);
} else {
if ((cpp * cstate->base.adjusted_mode.crtc_htotal / 512 < 1) &&
(plane_bytes_per_line / 512 < 1))
selected_result = method2;
- else if ((ddb_allocation / plane_blocks_per_line) >= 1)
- selected_result = min(method1, method2);
+ else if ((ddb_allocation /
+ fixed_16_16_to_u32_round_up(plane_blocks_per_line)) >= 1)
+ selected_result = min_fixed_16_16(method1, method2);
else
selected_result = method1;
}
- res_blocks = selected_result + 1;
- res_lines = DIV_ROUND_UP(selected_result, plane_blocks_per_line);
+ res_blocks = fixed_16_16_to_u32_round_up(selected_result) + 1;
+ res_lines = DIV_ROUND_UP(selected_result.val,
+ plane_blocks_per_line.val);
if (level >= 1 && level <= 7) {
if (y_tiled) {
- res_blocks += y_tile_minimum;
+ res_blocks += fixed_16_16_to_u32_round_up(y_tile_minimum);
res_lines += y_min_scanlines;
} else {
res_blocks++;