RE: [PATCH] ARM: delay: avoid clang -Wtautological-constant warning
From: David Laight <hidden>
Date: 2021-03-24 23:15:47
Also in:
lkml
From: Arnd Bergmann
Sent: 23 March 2021 13:20
Passing an 8-bit constant into delay() triggers a warning when building
with 'make W=1' using clang:
drivers/clk/actions/owl-pll.c:182:2: error: result of comparison of constant 2000 with expression of
type 'u8' (aka 'unsigned char') is always false [-Werror,-Wtautological-constant-out-of-range-compare]
udelay(pll_hw->delay);
^~~~~~~~~~~~~~~~~~~~~
arch/arm/include/asm/delay.h:84:9: note: expanded from macro 'udelay'
((n) > (MAX_UDELAY_MS * 1000) ? __bad_udelay() : \
~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~
arch/arm/mach-omap2/wd_timer.c:89:3: error: result of comparison of constant 2000 with expression of
type 'u8' (aka 'unsigned char') is always false [-Werror,-Wtautological-constant-out-of-range-compare]
udelay(oh->class->sysc->srst_udelay);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Shut up the warning by adding a cast to a 64-bit number. A cast to 'int'
would usually be sufficient, but would fail to cause a link-time error
for large 64-bit constants.Adding 0u probably has the desired effect - without any side effects of a cast. David
quoted hunk ↗ jump to hunk
Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- arch/arm/include/asm/delay.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/arch/arm/include/asm/delay.h b/arch/arm/include/asm/delay.h index 4f80b72372b4..1bb6417a3a83 100644 --- a/arch/arm/include/asm/delay.h +++ b/arch/arm/include/asm/delay.h@@ -81,7 +81,7 @@ extern void __bad_udelay(void); #define udelay(n) \ (__builtin_constant_p(n) ? \ - ((n) > (MAX_UDELAY_MS * 1000) ? __bad_udelay() : \ + ((u64)(n) > (MAX_UDELAY_MS * 1000) ? __bad_udelay() : \ __const_udelay((n) * UDELAY_MULT)) : \ __udelay(n)) --2.29.2
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