On Tue, Jun 15, 2021 at 04:19:03PM +0200, Maciej W. Rozycki wrote: > On Tue, 15 Jun 2021, Greg Kroah-Hartman wrote: > > > This patch series causes the following build warning to be added: > > > > drivers/tty/serial/8250/8250_pci.c: In function ‘pci_oxsemi_tornado_setup’: > > drivers/tty/serial/8250/8250_pci.c:1258:32: warning: unsigned conversion from ‘int’ to ‘unsigned char’ changes value from ‘-129’ to ‘127’ [-Woverflow] > > 1258 | up->mcr_mask = ~UART_MCR_CLKSEL; > > | ^ > > > > > > Can you fix this up and resend? > > I've seen that, but that's not a problem with my change, but rather with > <linux/serial_reg.h> making this macro (and the remaining ones from this > group) expand to a signed constant (0x80 rather than 0x80u). As your change causes it to show up, it must have something to do with it :) > I can fix the header, but that would be a separate change, and mind too > that this is a user header, so it's not clear to me what the impact might > be on user apps making use of it. You can not change the uapi header, why would you want to? > We could use a GCC pragma to suppress the warning temporarily across this > piece of code, but it's not clear to me either what our policy has been on > such approach. What pragma? > Thoughts? Why does your change cause this to show up? > NB casting UART_MCR_CLKSEL here to an unsigned type does not help as GCC > still sees the original constant through the cast; I've already tried that > of course. > > Last but not least: do we need to have this warning enabled in the first > place? No idea, but that's a different discussion, with a different group of people :) thanks, greg k-h
