drm/radeon/kms: handle the case of no active displays properly in the bandwidth code

Logic was:
if (mode0 && mode1)
else if (mode0)
else

Should be:
if (mode0 && mode1)
else if (mode0)
else if (mode1)

Otherwise we may end up calculating the priority regs with
unitialized values.

Fixes:
https://bugzilla.kernel.org/show_bug.cgi?id=16492

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Cc: stable@kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/rs690.c

@@ -398,7 +398,9 @@ void rs690_bandwidth_update(struct radeon_device *rdev)
 	struct drm_display_mode *mode1 = NULL;
 	struct rs690_watermark wm0;
 	struct rs690_watermark wm1;
-	u32 tmp, d1mode_priority_a_cnt, d2mode_priority_a_cnt;
+	u32 tmp;
+	u32 d1mode_priority_a_cnt = S_006548_D1MODE_PRIORITY_A_OFF(1);
+	u32 d2mode_priority_a_cnt = S_006548_D1MODE_PRIORITY_A_OFF(1);
 	fixed20_12 priority_mark02, priority_mark12, fill_rate;
 	fixed20_12 a, b;
 
@@ -495,10 +497,6 @@ void rs690_bandwidth_update(struct radeon_device *rdev)
 			d1mode_priority_a_cnt |= S_006548_D1MODE_PRIORITY_A_ALWAYS_ON(1);
 			d2mode_priority_a_cnt |= S_006D48_D2MODE_PRIORITY_A_ALWAYS_ON(1);
 		}
-		WREG32(R_006548_D1MODE_PRIORITY_A_CNT, d1mode_priority_a_cnt);
-		WREG32(R_00654C_D1MODE_PRIORITY_B_CNT, d1mode_priority_a_cnt);
-		WREG32(R_006D48_D2MODE_PRIORITY_A_CNT, d2mode_priority_a_cnt);
-		WREG32(R_006D4C_D2MODE_PRIORITY_B_CNT, d2mode_priority_a_cnt);
 	} else if (mode0) {
 		if (dfixed_trunc(wm0.dbpp) > 64)
 			a.full = dfixed_mul(wm0.dbpp, wm0.num_line_pair);
@@ -528,13 +526,7 @@ void rs690_bandwidth_update(struct radeon_device *rdev)
 		d1mode_priority_a_cnt = dfixed_trunc(priority_mark02);
 		if (rdev->disp_priority == 2)
 			d1mode_priority_a_cnt |= S_006548_D1MODE_PRIORITY_A_ALWAYS_ON(1);
-		WREG32(R_006548_D1MODE_PRIORITY_A_CNT, d1mode_priority_a_cnt);
-		WREG32(R_00654C_D1MODE_PRIORITY_B_CNT, d1mode_priority_a_cnt);
-		WREG32(R_006D48_D2MODE_PRIORITY_A_CNT,
-			S_006D48_D2MODE_PRIORITY_A_OFF(1));
-		WREG32(R_006D4C_D2MODE_PRIORITY_B_CNT,
-			S_006D4C_D2MODE_PRIORITY_B_OFF(1));
-	} else {
+	} else if (mode1) {
 		if (dfixed_trunc(wm1.dbpp) > 64)
 			a.full = dfixed_mul(wm1.dbpp, wm1.num_line_pair);
 		else
@@ -563,13 +555,12 @@ void rs690_bandwidth_update(struct radeon_device *rdev)
 		d2mode_priority_a_cnt = dfixed_trunc(priority_mark12);
 		if (rdev->disp_priority == 2)
 			d2mode_priority_a_cnt |= S_006D48_D2MODE_PRIORITY_A_ALWAYS_ON(1);
-		WREG32(R_006548_D1MODE_PRIORITY_A_CNT,
-			S_006548_D1MODE_PRIORITY_A_OFF(1));
-		WREG32(R_00654C_D1MODE_PRIORITY_B_CNT,
-			S_00654C_D1MODE_PRIORITY_B_OFF(1));
-		WREG32(R_006D48_D2MODE_PRIORITY_A_CNT, d2mode_priority_a_cnt);
-		WREG32(R_006D4C_D2MODE_PRIORITY_B_CNT, d2mode_priority_a_cnt);
 	}
+
+	WREG32(R_006548_D1MODE_PRIORITY_A_CNT, d1mode_priority_a_cnt);
+	WREG32(R_00654C_D1MODE_PRIORITY_B_CNT, d1mode_priority_a_cnt);
+	WREG32(R_006D48_D2MODE_PRIORITY_A_CNT, d2mode_priority_a_cnt);
+	WREG32(R_006D4C_D2MODE_PRIORITY_B_CNT, d2mode_priority_a_cnt);
 }
 
 uint32_t rs690_mc_rreg(struct radeon_device *rdev, uint32_t reg)

drivers/gpu/drm/radeon/rv515.c

@@ -927,7 +927,9 @@ void rv515_bandwidth_avivo_update(struct radeon_device *rdev)
 	struct drm_display_mode *mode1 = NULL;
 	struct rv515_watermark wm0;
 	struct rv515_watermark wm1;
-	u32 tmp, d1mode_priority_a_cnt, d2mode_priority_a_cnt;
+	u32 tmp;
+	u32 d1mode_priority_a_cnt = MODE_PRIORITY_OFF;
+	u32 d2mode_priority_a_cnt = MODE_PRIORITY_OFF;
 	fixed20_12 priority_mark02, priority_mark12, fill_rate;
 	fixed20_12 a, b;
 
@@ -1001,10 +1003,6 @@ void rv515_bandwidth_avivo_update(struct radeon_device *rdev)
 			d1mode_priority_a_cnt |= MODE_PRIORITY_ALWAYS_ON;
 			d2mode_priority_a_cnt |= MODE_PRIORITY_ALWAYS_ON;
 		}
-		WREG32(D1MODE_PRIORITY_A_CNT, d1mode_priority_a_cnt);
-		WREG32(D1MODE_PRIORITY_B_CNT, d1mode_priority_a_cnt);
-		WREG32(D2MODE_PRIORITY_A_CNT, d2mode_priority_a_cnt);
-		WREG32(D2MODE_PRIORITY_B_CNT, d2mode_priority_a_cnt);
 	} else if (mode0) {
 		if (dfixed_trunc(wm0.dbpp) > 64)
 			a.full = dfixed_div(wm0.dbpp, wm0.num_line_pair);
@@ -1034,11 +1032,7 @@ void rv515_bandwidth_avivo_update(struct radeon_device *rdev)
 		d1mode_priority_a_cnt = dfixed_trunc(priority_mark02);
 		if (rdev->disp_priority == 2)
 			d1mode_priority_a_cnt |= MODE_PRIORITY_ALWAYS_ON;
-		WREG32(D1MODE_PRIORITY_A_CNT, d1mode_priority_a_cnt);
-		WREG32(D1MODE_PRIORITY_B_CNT, d1mode_priority_a_cnt);
-		WREG32(D2MODE_PRIORITY_A_CNT, MODE_PRIORITY_OFF);
-		WREG32(D2MODE_PRIORITY_B_CNT, MODE_PRIORITY_OFF);
-	} else {
+	} else if (mode1) {
 		if (dfixed_trunc(wm1.dbpp) > 64)
 			a.full = dfixed_div(wm1.dbpp, wm1.num_line_pair);
 		else
@@ -1067,11 +1061,12 @@ void rv515_bandwidth_avivo_update(struct radeon_device *rdev)
 		d2mode_priority_a_cnt = dfixed_trunc(priority_mark12);
 		if (rdev->disp_priority == 2)
 			d2mode_priority_a_cnt |= MODE_PRIORITY_ALWAYS_ON;
-		WREG32(D1MODE_PRIORITY_A_CNT, MODE_PRIORITY_OFF);
-		WREG32(D1MODE_PRIORITY_B_CNT, MODE_PRIORITY_OFF);
-		WREG32(D2MODE_PRIORITY_A_CNT, d2mode_priority_a_cnt);
-		WREG32(D2MODE_PRIORITY_B_CNT, d2mode_priority_a_cnt);
 	}
+
+	WREG32(D1MODE_PRIORITY_A_CNT, d1mode_priority_a_cnt);
+	WREG32(D1MODE_PRIORITY_B_CNT, d1mode_priority_a_cnt);
+	WREG32(D2MODE_PRIORITY_A_CNT, d2mode_priority_a_cnt);
+	WREG32(D2MODE_PRIORITY_B_CNT, d2mode_priority_a_cnt);
 }
 
 void rv515_bandwidth_update(struct radeon_device *rdev)