Messages in this thread Patch in this message | | | Subject | Re: About commit "io: change inX() to have their own IO barrier overrides" | From | John Garry <> | Date | Fri, 6 Mar 2020 10:39:59 +0000 |
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On 06/03/2020 07:54, Arnd Bergmann wrote: > On Fri, Mar 6, 2020 at 4:44 AM Sinan Kaya <okaya@kernel.org> wrote: >> >> On 3/3/2020 11:40 AM, Arnd Bergmann wrote: >>>> - ret = read##bw(PCI_IOBASE + addr); >>>> + __io_pbr(); >>>> + ret = __raw_read##bw(PCI_IOBASE + addr); >>>> + __io_pbr(); >>> __io_par(); >>> >> >> Why do we need to change read##bw above? >> >> read##bw already provides strong ordering guarantees across multiple >> architectures. > > The exact semantics of inl() and readl() are slightly different, so they > have distinct sets of barriers in the asm-generic/io.h implementation. > > For instance, the arm64 architectures defines in_par() as '__iormb(v)', > but defines __io_ar() as a '__rmb()'. Similarly, riscv defines them > as "fence i,ior" and "fence i,r". > > You could argue that the definitions are wrong (I have not checked the > history of the definitions), but as long as the inb() in asm-generic/io.h > uses those, the implementation in lib/logic_pio.c uses the same ones > to make the two behave the same way. >
So the change would look like:
-- a/lib/logic_pio.c +++ b/lib/logic_pio.c @@ -229,13 +229,21 @@ unsigned long logic_pio_trans_cpuaddr(resource_size_t addr) }
#if defined(CONFIG_INDIRECT_PIO) && defined(PCI_IOBASE) + +#define logic_in_to_cpu_b(x) (x) +#define logic_in_to_cpu_w(x) __le16_to_cpu(x) +#define logic_in_to_cpu_l(x) __le32_to_cpu(x) + #define BUILD_LOGIC_IO(bw, type) \ type logic_in##bw(unsigned long addr) \ { \ type ret = (type)~0; \ \ if (addr < MMIO_UPPER_LIMIT) { \ - ret = read##bw(PCI_IOBASE + addr); \ + void __iomem *_addr = PCI_IOBASE + addr; \ + __io_pbr(); \ + ret = logic_in_to_cpu_##bw(__raw_read##bw(_addr)); \ + __io_par(ret); \ } else if (addr >= MMIO_UPPER_LIMIT && addr < IO_SPACE_LIMIT) {\ struct logic_pio_hwaddr *entry = find_io_rang
We could prob combine the le_to_cpu and __raw_read into a single macro. John
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