[PATCH 14/27] drm/amd/display: WBSCL filter init calculation fixes

[Harry Wentland]

From: Ken Chalmers <ken.chalmers at amd.com>

* Previous code did some calculations with a mix of normal integers and
  integers aligned as U2.24 fixed-point values.
* There were bugs in the conversion of the final result into the
  S4.19 values required for the registers.

Signed-off-by: Ken Chalmers <ken.chalmers at amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng at amd.com>
Acked-by: Harry Wentland <harry.wentland at amd.com>
---
 drivers/gpu/drm/amd/display/dc/basics/fixpt31_32.c | 9 +++++++++
 drivers/gpu/drm/amd/display/include/fixed31_32.h   | 3 +++
 2 files changed, 12 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/dc/basics/fixpt31_32.c b/drivers/gpu/drm/amd/display/dc/basics/fixpt31_32.c
index 011a97f82fb6..8a9bba879207 100644
--- a/drivers/gpu/drm/amd/display/dc/basics/fixpt31_32.c
+++ b/drivers/gpu/drm/amd/display/dc/basics/fixpt31_32.c
@@ -593,3 +593,12 @@ uint32_t dal_fixed31_32_clamp_u0d10(
 {
 	return clamp_ux_dy(arg.value, 0, 10, 1);
 }
+
+int32_t dal_fixed31_32_s4d19(
+	struct fixed31_32 arg)
+{
+	if (arg.value < 0)
+		return -(int32_t)ux_dy(dal_fixed31_32_abs(arg).value, 4, 19);
+	else
+		return ux_dy(arg.value, 4, 19);
+}
diff --git a/drivers/gpu/drm/amd/display/include/fixed31_32.h b/drivers/gpu/drm/amd/display/include/fixed31_32.h
index 4badaedbaadd..0de258622c12 100644
--- a/drivers/gpu/drm/amd/display/include/fixed31_32.h
+++ b/drivers/gpu/drm/amd/display/include/fixed31_32.h
@@ -470,4 +470,7 @@ uint32_t dal_fixed31_32_clamp_u0d14(
 uint32_t dal_fixed31_32_clamp_u0d10(
 	struct fixed31_32 arg);
 
+int32_t dal_fixed31_32_s4d19(
+	struct fixed31_32 arg);
+
 #endif
-- 
2.14.1