On Tue, Aug 9, 2022 at 6:08 PM Nathan Chancellor nathan@kernel.org 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/82afc9b169a67e8b8a1862fb9c41a2cd... Signed-off-by: Nathan Chancellor nathan@kernel.org
Ah yes, my favorite, signed one bit integers...thanks for the patch. Reviewed-by: Nick Desaulniers ndesaulniers@google.com
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