Hi Linus, On 29-08-20, 14:20, Linus Torvalds wrote: > On Sat, Aug 29, 2020 at 1:40 PM Guenter Roeck <li...@roeck-us.net> wrote: > > > > Except for > > > > CHECK: spaces preferred around that '+' (ctx:VxV) > > #29: FILE: drivers/dma/fsldma.h:223: > > + u32 val_lo = in_be32((u32 __iomem *)addr+1); > > Added spaces. > > > I don't see anything wrong with it either, so > > > > Reviewed-by: Guenter Roeck <li...@roeck-us.net> > > > > Since I didn't see the real problem with the original code, > > I'd take that with a grain of salt, though. > > Well, honestly, the old code was so confused that just making it build > is clearly already an improvement even if everything else were to be > wrong. > > So I committed my "fix". If it turns out there's more wrong in there > and somebody tests it, we can fix it again. But now it hopefully > compiles, at least. > > My bet is that if that driver ever worked on ppc32, it will continue > to work whatever we do to that function. > > I _think_ the old code happened to - completely by mistake - get the > value right for the case of "little endian access, with dma_addr_t > being 32-bit". Because then it would still read the upper bits wrong, > but the cast to dma_addr_t would then throw those bits away. And the > lower bits would be right. > > But for big-endian accesses or for ARCH_DMA_ADDR_T_64BIT it really > looks like it always returned a completely incorrect value. > > And again - the driver may have worked even with that completely > incorrect value, since the use of it seems to be very incidental.
Thank you for the fix. Acked-By: Vinod Koul <vk...@kernel.org> > > In either case ("it didn't work before" or "it worked because the > value doesn't really matter"), I don't think I could possibly have > made things worse. > > Famous last words. I guess no one tested this on 32bits seems to have caused this. -- ~Vinod