drm/i915: Deobfuscate wm linetime calculation

intel_get_linetime_us() is a mess. Rewrite it in a straightforward
manner. Also the checks for the !active and pixel_rate==0 are
completely pointless here since we know that the plane is visible.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250919180838.10498-3-ville.syrjala@linux.intel.com
Reviewed-by: Vinod Govindapillai <vinod.govindapillai@intel.com>

diff --git a/drivers/gpu/drm/i915/display/skl_watermark.c b/drivers/gpu/drm/i915/display/skl_watermark.c
index f73d1d24a488bae6eb13f68dd754ece8c2e8ac56..93cad11e0b31a5dca60f757c5c212b43cb2f4a1d 100644 (file)
--- a/drivers/gpu/drm/i915/display/skl_watermark.c
+++ b/drivers/gpu/drm/i915/display/skl_watermark.c
@@ -1636,24 +1636,12 @@ skl_wm_method2(u32 pixel_rate, u32 pipe_htotal, u32 latency,
        return ret;
 }
 
-static uint_fixed_16_16_t
+static int
 intel_get_linetime_us(const struct intel_crtc_state *crtc_state,
                      int pixel_rate)
 {
-       struct intel_display *display = to_intel_display(crtc_state);
-       u32 crtc_htotal;
-       uint_fixed_16_16_t linetime_us;
-
-       if (!crtc_state->hw.active)
-               return u32_to_fixed16(0);
-
-       if (drm_WARN_ON(display->drm, pixel_rate == 0))
-               return u32_to_fixed16(0);
-
-       crtc_htotal = crtc_state->hw.pipe_mode.crtc_htotal;
-       linetime_us = div_fixed16(crtc_htotal * 1000, pixel_rate);
-
-       return linetime_us;
+       return DIV_ROUND_UP(crtc_state->hw.pipe_mode.crtc_htotal * 1000,
+                           pixel_rate);
 }
 
 static int
@@ -1741,8 +1729,7 @@ skl_compute_wm_params(const struct intel_crtc_state *crtc_state,
        wp->y_tile_minimum = mul_u32_fixed16(wp->y_min_scanlines,
                                             wp->plane_blocks_per_line);
 
-       wp->linetime_us = fixed16_to_u32_round_up(intel_get_linetime_us(crtc_state,
-                                                                       plane_pixel_rate));
+       wp->linetime_us = intel_get_linetime_us(crtc_state, plane_pixel_rate);
 
        return 0;
 }