linux-kernel - [PATCH] arm64/prefetch: fix a -Wtype-limits warning

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Message-Id: <1564780084-29591-1-git-send-email-cai@lca.pw>
Date:   Fri,  2 Aug 2019 17:08:04 -0400
From:   Qian Cai <cai@....pw>
To:     will@...nel.org, catalin.marinas@....com
Cc:     rrichter@...ium.com, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Qian Cai <cai@....pw>
Subject: [PATCH] arm64/prefetch: fix a -Wtype-limits warning

The commit d5370f754875 ("arm64: prefetch: add alternative pattern for
CPUs without a prefetcher") introduced MIDR_IS_CPU_MODEL_RANGE() to be
used in has_no_hw_prefetch() with rv_min=0 which generates a compilation
warning from GCC,

In file included from ./arch/arm64/include/asm/cache.h:8,
                 from ./include/linux/cache.h:6,
                 from ./include/linux/printk.h:9,
                 from ./include/linux/kernel.h:15,
                 from ./include/linux/cpumask.h:10,
                 from arch/arm64/kernel/cpufeature.c:11:
arch/arm64/kernel/cpufeature.c: In function 'has_no_hw_prefetch':
./arch/arm64/include/asm/cputype.h:59:26: warning: comparison of
unsigned expression >= 0 is always true [-Wtype-limits]
  _model == (model) && rv >= (rv_min) && rv <= (rv_max);  \
                          ^~
arch/arm64/kernel/cpufeature.c:889:9: note: in expansion of macro
'MIDR_IS_CPU_MODEL_RANGE'
  return MIDR_IS_CPU_MODEL_RANGE(midr, MIDR_THUNDERX,
         ^~~~~~~~~~~~~~~~~~~~~~~

Fix it by making rv_min=1.

Signed-off-by: Qian Cai <cai@....pw>
---
 arch/arm64/kernel/cpufeature.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index f29f36a65175..7d15cf6d62c1 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -883,7 +883,7 @@ static bool has_no_hw_prefetch(const struct arm64_cpu_capabilities *entry, int _
 
 	/* Cavium ThunderX pass 1.x and 2.x */
 	return MIDR_IS_CPU_MODEL_RANGE(midr, MIDR_THUNDERX,
-		MIDR_CPU_VAR_REV(0, 0),
+		MIDR_CPU_VAR_REV(0, 1),
 		MIDR_CPU_VAR_REV(1, MIDR_REVISION_MASK));
 }
 
-- 
1.8.3.1