Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: [PATCH 4/8] tty/serial: add generic serial earlycon | Date | Sat, 19 Apr 2014 13:32:24 +0200 |
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On Thursday 17 April 2014, Rob Herring wrote: > On Mon, Mar 24, 2014 at 10:42 AM, Arnd Bergmann <arnd@arndb.de> wrote: > > On Monday 24 March 2014 08:36:46 Rob Herring wrote: > >> On Mon, Mar 24, 2014 at 6:29 AM, Arnd Bergmann <arnd@arndb.de> wrote: > >> > On Monday 24 March 2014 11:22:03 Catalin Marinas wrote: > >> >> On Fri, Mar 21, 2014 at 09:08:44PM +0000, Rob Herring wrote: > >> >> > diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c > >> >> > new file mode 100644 > >> >> > index 0000000..241757a > >> >> > --- /dev/null > >> >> > +++ b/drivers/tty/serial/earlycon.c > >> >> [...] > >> >> > +static void __iomem * __init earlycon_map(unsigned long paddr, size_t size) > >> >> > +{ > >> >> > + void __iomem *base; > >> >> > +#ifdef CONFIG_FIX_EARLYCON_MEM > >> >> > + set_fixmap_nocache(FIX_EARLYCON_MEM_BASE, paddr & PAGE_MASK); > >> >> > + base = (void __iomem *)__fix_to_virt(FIX_EARLYCON_MEM_BASE); > >> >> > + base += paddr & ~PAGE_MASK; > >> >> > +#else > >> >> > + base = ioremap_nocache(paddr, size); > >> >> > +#endif > >> >> > >> >> Just curious why not set_fixmap_io (and plain ioremap)? > >> > > >> > Good point. Note that ioremap_nocache() is the same as ioremap() > >> > on *all* architectures. > > Did you mean "not the same"?
No
> Why are there 2 flavors if they are > always the same.
I assume it's just a mistake someone made a long time ago and nobody ever changed it because they didn't want to break obscure code.
x86 seems to be a bit odd here, because is has both page-table and MTRR method of setting up whether an access can be cached or not. This may have led to the introduction of the _nocache variant, when the regular ioremap was already uncached on all other architectures but cached on x86.
Arnd
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