On Thu, Sep 29, 2016 at 04:26:52PM -0500, Steve Wise wrote: > > +/* Generally speaking, PCI systems auto-byteswap on PCI accesses, so this is > > + probably wrong */ > > +#define cpu_to_pci32(val) htole32(val) > > If this was wrong, then nothing would work. So I think you should > remove the comment. I added the comment because cxgb* was the only provider that seemed to be obviously byte swapping MMIO. Since htole32 is a NOP on x86 and ARM64 the driver would work fine with or without it. Do you know this driver works on big endian powerpc? That would help answer the question for sure. I looked at this some more, and I still don't really know what is the right answer. In the kernel the swapping behavior of 'writel' is architecture (and sometimes even platform) specific. Looking at the kernel headers suggests that BE PPC needs an explicit swap and BE ARM does not (eg the hardware swaps). Maybe. There are a lot of layers of macros in this area.. However, I can't find an obvious swap in mlx4, which I think is the most widely tested provider. Does it work on BE PPC? One of the things I'd like to see done is to consolidate the mmio accessors.. The note was a reminder to try and figure out what is actually right here.. Appreciate any help! Jason -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
