From a7e46317722ccdac6ae3bdb9476a1ec21b7aab6d Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Mon, 25 Jan 2016 17:02:24 +0100 Subject: [PATCH] mfd: db8500: Avoid uninitialized variable reference The prcmu_config_clkout() function ensures that the 'clkout' argument can only be '0' or '1' using an appropriate BUG_ON(), so the compiler should know that the div_mask, mask, and bits variables are always initialized later on. However, it doesn't understand this in gcc-5.2 and produces a false positive warning instead: drivers/mfd/db8500-prcmu.c: In function 'prcmu_config_clkout': drivers/mfd/db8500-prcmu.c:762:10: error: 'div_mask' may be used uninitialized in this function [-Werror=maybe-uninitialized] if (val & div_mask) { ^ drivers/mfd/db8500-prcmu.c:769:13: error: 'mask' may be used uninitialized in this function [-Werror=maybe-uninitialized] if ((val & mask & ~div_mask) != bits) { ^ drivers/mfd/db8500-prcmu.c:757:7: error: 'bits' may be used uninitialized in this function [-Werror=maybe-uninitialized] Replacing the switch() statement with an equivalent if() lets gcc figure this out reliably and avoids the warnings. Signed-off-by: Arnd Bergmann Acked-by: Linus Walleij Signed-off-by: Lee Jones --- drivers/mfd/db8500-prcmu.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/drivers/mfd/db8500-prcmu.c b/drivers/mfd/db8500-prcmu.c index e6e4bacb09ee..2f4a1279b094 100644 --- a/drivers/mfd/db8500-prcmu.c +++ b/drivers/mfd/db8500-prcmu.c @@ -739,20 +739,17 @@ int prcmu_config_clkout(u8 clkout, u8 source, u8 div) if (!div && !requests[clkout]) return -EINVAL; - switch (clkout) { - case 0: + if (clkout == 0) { div_mask = PRCM_CLKOCR_CLKODIV0_MASK; mask = (PRCM_CLKOCR_CLKODIV0_MASK | PRCM_CLKOCR_CLKOSEL0_MASK); bits = ((source << PRCM_CLKOCR_CLKOSEL0_SHIFT) | (div << PRCM_CLKOCR_CLKODIV0_SHIFT)); - break; - case 1: + } else { div_mask = PRCM_CLKOCR_CLKODIV1_MASK; mask = (PRCM_CLKOCR_CLKODIV1_MASK | PRCM_CLKOCR_CLKOSEL1_MASK | PRCM_CLKOCR_CLK1TYPE); bits = ((source << PRCM_CLKOCR_CLKOSEL1_SHIFT) | (div << PRCM_CLKOCR_CLKODIV1_SHIFT)); - break; } bits &= mask; -- 2.20.1