On Tue, Aug 9, 2022 at 6:08 PM Nathan Chancellor <nathan@xxxxxxxxxx> wrote:
>
> A recent change in clang strengthened its -Wbitfield-constant-conversion
> to warn when 1 is assigned to a 1-bit signed integer bitfield, as it can
> only be 0 or -1, not 1:
>
> sound/soc/atmel/mchp-spdiftx.c:505:20: error: implicit truncation from 'int' to bit-field changes value from 1 to -1 [-Werror,-Wbitfield-constant-conversion]
> dev->gclk_enabled = 1;
> ^ ~
> 1 error generated.
>
> The actual value of the field is never checked, just that it is not
> zero, so there is not a real bug here. However, it is simple enough to
> silence the warning by making the bitfield unsigned, which matches the
> mchp-spdifrx driver.
>
> Fixes: 06ca24e98e6b ("ASoC: mchp-spdiftx: add driver for S/PDIF TX Controller")
> Link: https://github.com/ClangBuiltLinux/linux/issues/1686
> Link: https://github.com/llvm/llvm-project/commit/82afc9b169a67e8b8a1862fb9c41a2cd974d6691
> Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx>
Ah yes, my favorite, signed one bit integers...thanks for the patch.
Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
grepping for `gclk_enabled`, we see three drivers with similar
duplication (single bit bitfields):
sound/soc/atmel/mchp-spdifrx.c
241: unsigned int gclk_enabled:1;
sound/soc/atmel/mchp-pdmc.c
118: u8 gclk_enabled:1;
sound/soc/atmel/mchp-spdiftx.c
200: int gclk_enabled:1;
> ---
> sound/soc/atmel/mchp-spdiftx.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/sound/soc/atmel/mchp-spdiftx.c b/sound/soc/atmel/mchp-spdiftx.c
> index 4850a177803d..ab2d7a791f39 100644
> --- a/sound/soc/atmel/mchp-spdiftx.c
> +++ b/sound/soc/atmel/mchp-spdiftx.c
> @@ -196,7 +196,7 @@ struct mchp_spdiftx_dev {
> struct clk *pclk;
> struct clk *gclk;
> unsigned int fmt;
> - int gclk_enabled:1;
> + unsigned int gclk_enabled:1;
> };
>
> static inline int mchp_spdiftx_is_running(struct mchp_spdiftx_dev *dev)
>
> base-commit: 15205c2829ca2cbb5ece5ceaafe1171a8470e62b
> --
> 2.37.1
>
--
Thanks,
~Nick Desaulniers
