drm/amd/display: Fix compiler warnings on high compiler warning levels

[why]
Enabling higher compiler warning levels results in many issues that can
be trivially resolved as well as some potentially critical issues.

[how]
Fix all compiler warnings found with various compilers and higher
warning levels.  Primarily, potentially uninitialized variables and
unreachable code.

Reviewed-by: Leo Li <sunpeng.li@amd.com>
Acked-by: Roman Li <roman.li@amd.com>
Signed-off-by: Aric Cyr <aric.cyr@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

8 files changed, 9 insertions, 16 deletions

diff --git a/drivers/gpu/drm/amd/display/dc/dml/dcn20/dcn20_fpu.c b/drivers/gpu/drm/amd/display/dc/dml/dcn20/dcn20_fpu.c
index 9c93a9f1eb0c..25d46c69464f 100644
--- a/drivers/gpu/drm/amd/display/dc/dml/dcn20/dcn20_fpu.c
+++ b/drivers/gpu/drm/amd/display/dc/dml/dcn20/dcn20_fpu.c
@@ -1102,8 +1102,6 @@ static enum dcn_zstate_support_state  decide_zstate_support(struct dc *dc, struc
 	} else {
 		return DCN_ZSTATE_SUPPORT_DISALLOW;
 	}
-
-	return DCN_ZSTATE_SUPPORT_DISALLOW;
 }
 
 static void dcn20_adjust_freesync_v_startup(
diff --git a/drivers/gpu/drm/amd/display/dc/dml/dcn30/display_mode_vba_30.c b/drivers/gpu/drm/amd/display/dc/dml/dcn30/display_mode_vba_30.c
index e7f4a2d491cc..e0b52db2c210 100644
--- a/drivers/gpu/drm/amd/display/dc/dml/dcn30/display_mode_vba_30.c
+++ b/drivers/gpu/drm/amd/display/dc/dml/dcn30/display_mode_vba_30.c
@@ -3535,7 +3535,6 @@ static double TruncToValidBPP(
 			return DesiredBPP;
 		}
 	}
-	return BPP_INVALID;
 }
 
 void dml30_ModeSupportAndSystemConfigurationFull(struct display_mode_lib *mode_lib)
diff --git a/drivers/gpu/drm/amd/display/dc/dml/dcn31/display_mode_vba_31.c b/drivers/gpu/drm/amd/display/dc/dml/dcn31/display_mode_vba_31.c
index adea459e7d36..33cf824c5da1 100644
--- a/drivers/gpu/drm/amd/display/dc/dml/dcn31/display_mode_vba_31.c
+++ b/drivers/gpu/drm/amd/display/dc/dml/dcn31/display_mode_vba_31.c
@@ -3679,7 +3679,6 @@ static double TruncToValidBPP(
 			return DesiredBPP;
 		}
 	}
-	return BPP_INVALID;
 }
 
 static noinline void CalculatePrefetchSchedulePerPlane(
diff --git a/drivers/gpu/drm/amd/display/dc/dml/dcn314/dcn314_fpu.c b/drivers/gpu/drm/amd/display/dc/dml/dcn314/dcn314_fpu.c
index fb21572750e8..21f637ae4add 100644
--- a/drivers/gpu/drm/amd/display/dc/dml/dcn314/dcn314_fpu.c
+++ b/drivers/gpu/drm/amd/display/dc/dml/dcn314/dcn314_fpu.c
@@ -310,7 +310,7 @@ int dcn314_populate_dml_pipes_from_context_fpu(struct dc *dc, struct dc_state *c
 {
 	int i, pipe_cnt;
 	struct resource_context *res_ctx = &context->res_ctx;
-	struct pipe_ctx *pipe;
+	struct pipe_ctx *pipe = 0;
 	bool upscaled = false;
 	const unsigned int max_allowed_vblank_nom = 1023;
 
diff --git a/drivers/gpu/drm/amd/display/dc/dml/dcn314/display_mode_vba_314.c b/drivers/gpu/drm/amd/display/dc/dml/dcn314/display_mode_vba_314.c
index 88e56889a68c..3242957d00c5 100644
--- a/drivers/gpu/drm/amd/display/dc/dml/dcn314/display_mode_vba_314.c
+++ b/drivers/gpu/drm/amd/display/dc/dml/dcn314/display_mode_vba_314.c
@@ -3788,7 +3788,6 @@ static double TruncToValidBPP(
 			return DesiredBPP;
 		}
 	}
-	return BPP_INVALID;
 }
 
 static noinline void CalculatePrefetchSchedulePerPlane(
diff --git a/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c b/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
index 80fccd4999a5..76399c66bc3b 100644
--- a/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
+++ b/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
@@ -1650,6 +1650,8 @@ double dml32_TruncToValidBPP(
 			MaxLinkBPP = 2 * MaxLinkBPP;
 	}
 
+	*RequiredSlots = dml_ceil(DesiredBPP / MaxLinkBPP * 64, 1);
+
 	if (DesiredBPP == 0) {
 		if (DSCEnable) {
 			if (MaxLinkBPP < MinDSCBPP)
@@ -1676,10 +1678,6 @@ double dml32_TruncToValidBPP(
 		else
 			return DesiredBPP;
 	}
-
-	*RequiredSlots = dml_ceil(DesiredBPP / MaxLinkBPP * 64, 1);
-
-	return BPP_INVALID;
 } // TruncToValidBPP
 
 double dml32_RequiredDTBCLK(
@@ -4291,7 +4289,7 @@ void dml32_CalculateWatermarksMALLUseAndDRAMSpeedChangeSupport(
 	unsigned int i, j, k;
 	unsigned int SurfaceWithMinActiveFCLKChangeMargin = 0;
 	unsigned int DRAMClockChangeSupportNumber = 0;
-	unsigned int LastSurfaceWithoutMargin;
+	unsigned int LastSurfaceWithoutMargin = 0;
 	unsigned int DRAMClockChangeMethod = 0;
 	bool FoundFirstSurfaceWithMinActiveFCLKChangeMargin = false;
 	double MinActiveFCLKChangeMargin = 0.;
@@ -5656,9 +5654,9 @@ void dml32_CalculateStutterEfficiency(
 	double LastZ8StutterPeriod = 0.0;
 	double LastStutterPeriod = 0.0;
 	unsigned int TotalNumberOfActiveOTG = 0;
-	double doublePixelClock;
-	unsigned int doubleHTotal;
-	unsigned int doubleVTotal;
+	double doublePixelClock = 0;
+	unsigned int doubleHTotal = 0;
+	unsigned int doubleVTotal = 0;
 	bool SameTiming = true;
 	double DETBufferingTimeY;
 	double SwathWidthYCriticalSurface = 0.0;
diff --git a/drivers/gpu/drm/amd/display/dc/dml/dcn35/dcn35_fpu.c b/drivers/gpu/drm/amd/display/dc/dml/dcn35/dcn35_fpu.c
index 714c2fe03c5f..60f251cf973b 100644
--- a/drivers/gpu/drm/amd/display/dc/dml/dcn35/dcn35_fpu.c
+++ b/drivers/gpu/drm/amd/display/dc/dml/dcn35/dcn35_fpu.c
@@ -439,7 +439,7 @@ int dcn35_populate_dml_pipes_from_context_fpu(struct dc *dc,
 {
 	int i, pipe_cnt;
 	struct resource_context *res_ctx = &context->res_ctx;
-	struct pipe_ctx *pipe;
+	struct pipe_ctx *pipe = 0;
 	bool upscaled = false;
 	const unsigned int max_allowed_vblank_nom = 1023;
 
diff --git a/drivers/gpu/drm/amd/display/dc/dml/dcn351/dcn351_fpu.c b/drivers/gpu/drm/amd/display/dc/dml/dcn351/dcn351_fpu.c
index b3ffab77cf88..5abf120ff075 100644
--- a/drivers/gpu/drm/amd/display/dc/dml/dcn351/dcn351_fpu.c
+++ b/drivers/gpu/drm/amd/display/dc/dml/dcn351/dcn351_fpu.c
@@ -474,7 +474,7 @@ int dcn351_populate_dml_pipes_from_context_fpu(struct dc *dc,
 {
 	int i, pipe_cnt;
 	struct resource_context *res_ctx = &context->res_ctx;
-	struct pipe_ctx *pipe;
+	struct pipe_ctx *pipe = 0;
 	bool upscaled = false;
 	const unsigned int max_allowed_vblank_nom = 1023;