+Marc Z On Mon, Nov 15, 2021 at 8:39 AM Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> wrote: > > On Mon, Nov 15, 2021 at 04:14:21PM +0200, Andy Shevchenko wrote: > > On Mon, Nov 15, 2021 at 4:01 PM Robin Murphy <robin.murphy@xxxxxxx> wrote: > > > On 2021-11-15 11:20, Andy Shevchenko wrote: > > > > Use BIT() as __GENMASK() is for internal use only. The rationale > > > > of switching to BIT() is to provide better generated code. The > > > > GENMASK() against non-constant numbers may produce an ugly assembler > > > > code. On contrary the BIT() is simply converted to corresponding shift > > > > operation. > > > > > > FWIW, If you care about code quality and want the compiler to do the > > > obvious thing, why not specify it as the obvious thing: > > > > > > u32 val = ~0 << msi->legacy_shift; > > > > Obvious and buggy (from the C standard point of view)? :-) > > Forgot to mention that BIT() is also makes it easy to avoid such mistake. > > > > Personally I don't think that abusing BIT() in the context of setting > > > multiple bits is any better than abusing __GENMASK()... > > > > No, BIT() is not abused here, but __GENMASK(). > > > > After all it's up to you, folks, consider that as a bug report. Couldn't we get rid of legacy_shift entirely if the legacy case sets up 'hwirq' as 24-31 rather than 0-7? Though the data for the MSI msg uses the hwirq. Rob
