2020-09-10 17:21:05

by Nathan Chancellor

[permalink] [raw]

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 <[email protected]>
---
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

2020-09-11 09:32:01

by Maxime Ripard

[permalink] [raw]

Subject: Re: [PATCH] drm/vc4: Fix bitwise OR versus ternary operator in vc4_plane_mode_set

---

On Thu, Sep 10, 2020 at 10:18:32AM -0700, Nathan Chancellor wrote:
> 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 <[email protected]>

Applied, thanks!
Maxime

---

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