[PATCH] ASoC: nau8810: use 64-bit arithmetic instead of 32-bit

[PATCH] ASoC: nau8810: use 64-bit arithmetic instead of 32-bit

[Gustavo A. R. Silva]

Add suffix ULL to constant 256 in order to give the compiler complete
information about the proper arithmetic to use.

Notice that such constant is used in a context that expects an
expression of type u64 (64 bits, unsigned) and the following
expression is currently being evaluated using 32-bit arithmetic:

256 * fs * 4 * nau8810_mclk_scaler[i] / 10

Addresses-Coverity-ID: 1357595 ("Unintentional integer overflow")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 sound/soc/codecs/nau8810.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/soc/codecs/nau8810.c b/sound/soc/codecs/nau8810.c
index bfd74b8..e7fd0b2 100644
--- a/sound/soc/codecs/nau8810.c
+++ b/sound/soc/codecs/nau8810.c
@@ -505,7 +505,7 @@ static int nau88l0_calc_pll(unsigned int pll_in,
 	f2_max = 0;
 	scal_sel = ARRAY_SIZE(nau8810_mclk_scaler);
 	for (i = 0; i < ARRAY_SIZE(nau8810_mclk_scaler); i++) {
-		f2 = 256 * fs * 4 * nau8810_mclk_scaler[i] / 10;
+		f2 = 256ULL * fs * 4 * nau8810_mclk_scaler[i] / 10;
 		if (f2 > NAU_PLL_FREQ_MIN && f2 < NAU_PLL_FREQ_MAX &&
 			f2_max < f2) {
 			f2_max = f2;
-- 
2.7.4

Re: [PATCH] ASoC: nau8810: use 64-bit arithmetic instead of 32-bit

[kbuild test robot]

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Hi Gustavo,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on asoc/for-next]
[also build test ERROR on v4.18-rc3 next-20180706]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Gustavo-A-R-Silva/ASoC-nau8810-use-64-bit-arithmetic-instead-of-32-bit/20180706-033309
base:   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-next
config: m68k-allyesconfig (attached as .config)
compiler: m68k-linux-gnu-gcc (Debian 7.2.0-11) 7.2.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        GCC_VERSION=7.2.0 make.cross ARCH=m68k 

All errors (new ones prefixed by >>):

   sound/soc/codecs/nau8810.o: In function `nau8810_set_pll':
>> nau8810.c:(.text+0x53c): undefined reference to `__udivdi3'

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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