Hi Michael,

On Sun, Mar 5, 2023 at 10:23 AM Michael Ellerman [off-list ref] wrote:

Baoquan He [off-list ref] writes:

quoted

ioremap_uc() is only meaningful on old x86-32 systems with the PAT
extension, and on ia64 with its slightly unconventional ioremap()
behavior, everywhere else this is the same as ioremap() anyway.

Here, remove the ioremap_uc() definition in architecutures other
than x86 and ia64. These architectures all have asm-generic/io.h
included and will have the default ioremap_uc() definition which
returns NULL.

Note: This changes the existing behaviour and could break code
calling ioremap_uc(). If any ARCH meets this breakage and really
needs a specific ioremap_uc() for its own usage, one ioremap_uc()
can be added in the ARCH.

I see one use in:

drivers/video/fbdev/aty/atyfb_base.c:        par->ati_regbase = ioremap_uc(info->fix.mmio_start, 0x1000);


Which isn't obviously x86/ia64 specific.

I'm pretty sure some powermacs (powerpc) use that driver.

I originally wrote that driver for CHRP, so yes.

Maybe that exact code path is only reachable on x86/ia64? But if so
please explain why.

Otherwise it looks like this series could break that driver on powerpc
at least.

Indeed.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds