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* [PATCH] [v3] spi: work around clang bug in SPI_BPW_RANGE_MASK()
@ 2019-03-07 15:54 Arnd Bergmann
  2019-03-11  9:11 ` Geert Uytterhoeven
                   ` (3 more replies)
  0 siblings, 4 replies; 10+ messages in thread
From: Arnd Bergmann @ 2019-03-07 15:54 UTC (permalink / raw)
  To: Mark Brown
  Cc: Rasmus Villemoes, Arnd Bergmann, Boris Brezillon, Linus Walleij,
	linux-spi, linux-kernel

Clang-8 evaluates both sides of a ?: expression to check for
valid arithmetic even in the side that is never taken. This
results in a build warning:

drivers/spi/spi-sh-msiof.c:1052:24: error: shift count >= width of type [-Werror,-Wshift-count-overflow]
        .bits_per_word_mask = SPI_BPW_RANGE_MASK(8, 32),
                              ^~~~~~~~~~~~~~~~~~~~~~~~~

Change the implementation to use the GENMASK() macro that does
what we want here but does not have a problem with the shift
count overflow.

Link: https://bugs.llvm.org/show_bug.cgi?id=38789
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
v3: use GENMASK() instead of open-coding it
v2: add a code comment
---
 include/linux/spi/spi.h | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 662b336aa2e4..b27386450089 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -444,8 +444,7 @@ struct spi_controller {
 	/* bitmask of supported bits_per_word for transfers */
 	u32			bits_per_word_mask;
 #define SPI_BPW_MASK(bits) BIT((bits) - 1)
-#define SPI_BIT_MASK(bits) (((bits) == 32) ? ~0U : (BIT(bits) - 1))
-#define SPI_BPW_RANGE_MASK(min, max) (SPI_BIT_MASK(max) - SPI_BIT_MASK(min - 1))
+#define SPI_BPW_RANGE_MASK(min, max) GENMASK((min) - 1, (max) - 1)
 
 	/* limits on transfer speed */
 	u32			min_speed_hz;
-- 
2.20.0


^ permalink raw reply related	[flat|nested] 10+ messages in thread

end of thread, other threads:[~2019-03-14 15:55 UTC | newest]

Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-03-07 15:54 [PATCH] [v3] spi: work around clang bug in SPI_BPW_RANGE_MASK() Arnd Bergmann
2019-03-11  9:11 ` Geert Uytterhoeven
2019-03-11 17:24 ` Applied "spi: work around clang bug in SPI_BPW_RANGE_MASK()" to the spi tree Mark Brown
2019-03-11 17:24   ` Mark Brown
2019-03-13 19:15   ` Geert Uytterhoeven
2019-03-13 21:01     ` Arnd Bergmann
2019-03-13 15:40 ` Mark Brown
2019-03-13 15:40   ` Mark Brown
2019-03-14 15:54 ` Mark Brown
2019-03-14 15:54   ` Mark Brown

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