On Tue, 15 Jun 2021, David Laight wrote: > > As I have noted above there is a data type signedness difference between > > `mcr_mask' and UART_MCR_CLKSEL. So we have the value of 0x80 (128). > > Once bitwise-complemented it becomes 0xffffff7f (-129). Once assigned to > > `mcr_mask' however it becomes 0x7f (127), which is considered an unsafe > > conversion between signed and unsigned integers by GCC, which is why the > > compiler complains about it. > > Blame the iso C standards committee for making integer promotions > 'value preserving' instead of 'sign preserving' as they were in K&R C. > > Try using ^ 0xffu instead of ~. Hmm, this is probably the least horrible way to paper it over, thanks. Even using a temporary variable (let alone a cast) does not help as GCC sees through it, and I've given up on converting <linux/serial_reg.h> to have e.g.: #define UART_MCR_CLKSEL _UL(0x80) /* Divide clock by 4 (TI16C752, EFR[4]=1) */ as I find that too messy with many of the comments wrapping up. And using a GCC pragma would require a messy compiler version check. I have posted an update with a path-of-least-resistance fix then along with the 4/4 as v2 of this series. Maciej
