linux-kernel - [PATCH] drm/vc4: Fix bitwise OR versus ternary operator in vc4_plane_mode

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Date:   Thu, 10 Sep 2020 10:18:32 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     Eric Anholt <eric@...olt.net>, Maxime Ripard <maxime@...no.tech>
Cc:     Dave Stevenson <dave.stevenson@...pberrypi.com>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        clang-built-linux@...glegroups.com,
        Nathan Chancellor <natechancellor@...il.com>
Subject: [PATCH] drm/vc4: Fix bitwise OR versus ternary operator in vc4_plane_mode_set

Clang warns:

drivers/gpu/drm/vc4/vc4_plane.c:901:27: warning: operator '?:' has lower
precedence than '|'; '|' will be evaluated first
[-Wbitwise-conditional-parentheses]
                                fb->format->has_alpha ?
                                ~~~~~~~~~~~~~~~~~~~~~ ^
drivers/gpu/drm/vc4/vc4_plane.c:901:27: note: place parentheses around
the '|' expression to silence this warning
                                fb->format->has_alpha ?
                                ~~~~~~~~~~~~~~~~~~~~~ ^
drivers/gpu/drm/vc4/vc4_plane.c:901:27: note: place parentheses around
the '?:' expression to evaluate it first
                                fb->format->has_alpha ?
                                ~~~~~~~~~~~~~~~~~~~~~~^
1 warning generated.

Add the parentheses as that was clearly intended, otherwise
SCALER5_CTL2_ALPHA_PREMULT won't be added to the list.

Fixes: c54619b0bfb3 ("drm/vc4: Add support for the BCM2711 HVS5")
Link: https://github.com/ClangBuiltLinux/linux/issues/1150
Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
---
 drivers/gpu/drm/vc4/vc4_plane.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_plane.c b/drivers/gpu/drm/vc4/vc4_plane.c
index 24d7e6db6fdd..89543fa8ca4d 100644
--- a/drivers/gpu/drm/vc4/vc4_plane.c
+++ b/drivers/gpu/drm/vc4/vc4_plane.c
@@ -898,8 +898,8 @@ static int vc4_plane_mode_set(struct drm_plane *plane,
 		vc4_dlist_write(vc4_state,
 				VC4_SET_FIELD(state->alpha >> 4,
 					      SCALER5_CTL2_ALPHA) |
-				fb->format->has_alpha ?
-					SCALER5_CTL2_ALPHA_PREMULT : 0 |
+				(fb->format->has_alpha ?
+					SCALER5_CTL2_ALPHA_PREMULT : 0) |
 				(mix_plane_alpha ?
 					SCALER5_CTL2_ALPHA_MIX : 0) |
 				VC4_SET_FIELD(fb->format->has_alpha ?

base-commit: 8c3c818c23a5bbce6ff180dd2ee04415241df77c
-- 
2.28.0