On Thu, Nov 12, 2020 at 09:27:15AM +0100, Miquel Raynal wrote: > Hi Sergey, > > Serge Semin <sergey.se...@baikalelectronics.ru> wrote on Wed, 11 Nov > 2020 22:22:59 +0300: > > > On Tue, Nov 10, 2020 at 04:35:56PM +0100, Miquel Raynal wrote: > > > Hi Serge, > > > > > > Serge Semin <sergey.se...@baikalelectronics.ru> wrote on Tue, 10 Nov > > > 2020 14:38:27 +0300: > > > > > > > Hello Miquel, > > > > > > > > A situation noted by the warning below won't cause any problem because > > > > the casting is done to a non-dereferenced variable. It is utilized > > > > as a pointer bias later in that function. Shall we just ignore the > > > > warning or still fix it somehow? > > > > >
> > > Do you think the cast to a !__iomem value is mandatory here? > > > > It's not mandatory to have the casting with no __iomem, but wouldn't > > doing like this: > > + shift = (ssize_t __iomem)src & 0x3; > > be looking weird? Really, is there a good way to somehow extract the first > > two bits of a __iomem pointer without getting the sparse warning? > > I asked around me, what about trying uintptr_t? Hm, that's weird. sparse gets happy if a casting to an unsigned type is used here. That's why the similar statement defined in bt1_rom_map_read() doesn't cause the sparse warning, while the statement with ssize_t does. Can people around explain whether that is just an internal sparse feature or there is a particular reason of having the unsigned types casting ignored by sparse in this case? I don't really understand why removing the __iomem attribute with casting to a signed type cause the warning, while casting to an unsigned type doesn't... Anyway I'll send a patch with the fix of using the uintptr_t casting here. Thanks for suggesting the solution. -Sergey > > Thanks, > Miquèl
