| Message ID | 1453737752-1960326-1-git-send-email-arnd@arndb.de |
|---|---|
| State | Accepted |
| Commit | a7e46317722ccdac6ae3bdb9476a1ec21b7aab6d |
| Headers | show |
On Mon, Jan 25, 2016 at 5:02 PM, Arnd Bergmann <arnd@arndb.de> wrote: > 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 <arnd@arndb.de> OK then.. Acked-by: Linus Walleij <linus.walleij@linaro.org> Yours, Linus Walleij
On Mon, 25 Jan 2016, Arnd Bergmann wrote: > 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 <arnd@arndb.de> > --- > drivers/mfd/db8500-prcmu.c | 7 ++----- > 1 file changed, 2 insertions(+), 5 deletions(-) Applied, thanks. > diff --git a/drivers/mfd/db8500-prcmu.c b/drivers/mfd/db8500-prcmu.c > index 12099b09a9a7..c0a86aeb1733 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; > -- Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog
diff --git a/drivers/mfd/db8500-prcmu.c b/drivers/mfd/db8500-prcmu.c index 12099b09a9a7..c0a86aeb1733 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;
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 <arnd@arndb.de> --- drivers/mfd/db8500-prcmu.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) -- 2.7.0