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>

1 files changed, 9 insertions, 14 deletions

diff --git a/drivers/gpu/drm/radeon/rv515.c b/drivers/gpu/drm/radeon/rv515.c
index b951b8790175..4d6e86041a9f 100644
--- a/drivers/gpu/drm/radeon/rv515.c
+++ b/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)