linux-kernel - [PATCH] soc/tegra: fuse: Fix bitwise vs. logical OR warning

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Date:   Thu, 21 Oct 2021 14:45:00 -0700
From:   Nathan Chancellor <nathan@...nel.org>
To:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>
Cc:     Nick Desaulniers <ndesaulniers@...gle.com>,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org,
        llvm@...ts.linux.dev, Nathan Chancellor <nathan@...nel.org>
Subject: [PATCH] soc/tegra: fuse: Fix bitwise vs. logical OR warning

A new warning in clang points out two instances where boolean
expressions are being used with a bitwise OR instead of logical OR:

drivers/soc/tegra/fuse/speedo-tegra20.c:72:9: warning: use of bitwise '|' with boolean operands [-Wbitwise-instead-of-logical]
                reg = tegra_fuse_read_spare(i) |
                      ^~~~~~~~~~~~~~~~~~~~~~~~~~
                                               ||
drivers/soc/tegra/fuse/speedo-tegra20.c:72:9: note: cast one or both operands to int to silence this warning
drivers/soc/tegra/fuse/speedo-tegra20.c:87:9: warning: use of bitwise '|' with boolean operands [-Wbitwise-instead-of-logical]
                reg = tegra_fuse_read_spare(i) |
                      ^~~~~~~~~~~~~~~~~~~~~~~~~~
                                               ||
drivers/soc/tegra/fuse/speedo-tegra20.c:87:9: note: cast one or both operands to int to silence this warning
2 warnings generated.

The motivation for the warning is that logical operations short circuit
while bitwise operations do not. In this case, it does not seem like
short circuiting is harmful so implement the suggested fix of changing
to a logical operation to fix the warning.

Link: https://github.com/ClangBuiltLinux/linux/issues/1488
Signed-off-by: Nathan Chancellor <nathan@...nel.org>
---
 drivers/soc/tegra/fuse/speedo-tegra20.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/soc/tegra/fuse/speedo-tegra20.c b/drivers/soc/tegra/fuse/speedo-tegra20.c
index 2546bddbab93..4984246605ae 100644
--- a/drivers/soc/tegra/fuse/speedo-tegra20.c
+++ b/drivers/soc/tegra/fuse/speedo-tegra20.c
@@ -69,7 +69,7 @@ void __init tegra20_init_speedo_data(struct tegra_sku_info *sku_info)
 
 	val = 0;
 	for (i = CPU_SPEEDO_MSBIT; i >= CPU_SPEEDO_LSBIT; i--) {
-		reg = tegra_fuse_read_spare(i) |
+		reg = tegra_fuse_read_spare(i) ||
 			tegra_fuse_read_spare(i + CPU_SPEEDO_REDUND_OFFS);
 		val = (val << 1) | (reg & 0x1);
 	}
@@ -84,7 +84,7 @@ void __init tegra20_init_speedo_data(struct tegra_sku_info *sku_info)
 
 	val = 0;
 	for (i = SOC_SPEEDO_MSBIT; i >= SOC_SPEEDO_LSBIT; i--) {
-		reg = tegra_fuse_read_spare(i) |
+		reg = tegra_fuse_read_spare(i) ||
 			tegra_fuse_read_spare(i + SOC_SPEEDO_REDUND_OFFS);
 		val = (val << 1) | (reg & 0x1);
 	}

base-commit: 519d81956ee277b4419c723adfb154603c2565ba
-- 
2.33.1.637.gf443b226ca