On Wed, Mar 26, 2025 at 12:59:57AM +0900, Vincent Mailhol via B4 Relay wrote: > From: Vincent Mailhol <mailhol.vinc...@wanadoo.fr> > > Add GENMASK_TYPE() which generalizes __GENMASK() to support different > types, and implement fixed-types versions of GENMASK() based on it. > The fixed-type version allows more strict checks to the min/max values > accepted, which is useful for defining registers like implemented by > i915 and xe drivers with their REG_GENMASK*() macros. > > The strict checks rely on shift-count-overflow compiler check to fail
-Wshift-count-overflow but it's not so important here. It's good that it's fixed in the comment. In any case if Yury wants/can do the change, it might be done when applying. (I.o.w. no need to resend) > the build if a number outside of the range allowed is passed. > Example: > > #define FOO_MASK GENMASK_U32(33, 4) > > will generate a warning like: > > include/linux/bits.h:51:27: error: right shift count >= width of type > [-Werror=shift-count-overflow] > 51 | type_max(t) >> (BITS_PER_TYPE(t) - 1 - (h))))) > | ^~ > > The result is casted to the corresponding fixed width type. For > example, GENMASK_U8() returns an u8. Note that because of the C > promotion rules, GENMASK_U8() and GENMASK_U16() will immediately be > promoted to int if used in an expression. Regardless, the main goal is > not to get the correct type, but rather to enforce more checks at > compile time. > > While GENMASK_TYPE() is crafted to cover all variants, including the > already existing GENMASK(), GENMASK_ULL() and GENMASK_U128(), for the > moment, only use it for the newly introduced GENMASK_U*(). The > consolidation will be done in a separate change. The change LGTM, FWIW, Reviewed-by: Andy Shevchenko <andriy.shevche...@linux.intel.com> -- With Best Regards, Andy Shevchenko
