On Tue, Nov 26, 2019 at 10:02:18AM +0100, Mateusz Holenko wrote: > śr., 20 lis 2019 o 20:26 Greg Kroah-Hartman > <gregkh@xxxxxxxxxxxxxxxxxxx> napisał(a): > > > > On Wed, Oct 23, 2019 at 11:47:04AM +0200, Mateusz Holenko wrote: > > > +#ifdef __LITTLE_ENDIAN > > > +# define LITEX_READ_REG(addr) ioread32(addr) > > > +# define LITEX_READ_REG_OFF(addr, off) ioread32(addr + off) > > > +# define LITEX_WRITE_REG(val, addr) iowrite32(val, addr) > > > +# define LITEX_WRITE_REG_OFF(val, addr, off) iowrite32(val, addr + off) > > > +#else > > > +# define LITEX_READ_REG(addr) ioread32be(addr) > > > +# define LITEX_READ_REG_OFF(addr, off) ioread32be(addr + off) > > > +# define LITEX_WRITE_REG(val, addr) iowrite32be(val, addr) > > > +# define LITEX_WRITE_REG_OFF(val, addr, off) iowrite32be(val, addr + off) > > > +#endif > > > > I just noticed this. > > > > Ick, this is not good. You will run into problems in the future with > > this, I can guarantee it. What about systems where the CPU is one > > endian and the hardware in the other? It will happen trust us. > > As mentioned in the previous comment, LiteX CSRs are guaranteed to be > always little-endian - this includes configurations with both > big-endian and little-endian CPUs. What enforces that guarantee? > The aim of including the ifdef section was exactly to target situation > where endianness is different for CPU and devices. As such this > approach *should* work. "should" :) We have seen it happen all the time that some hardware team hooks this up backwards, no matter what the "spec" required. So be careful here. good luck! greg k-h
