From: arnd@arndb•de (Arnd Bergmann)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 4/8] tty/serial: add generic serial earlycon
Date: Sat, 19 Apr 2014 13:32:24 +0200 [thread overview]
Message-ID: <201404191332.24392.arnd@arndb.de> (raw)
In-Reply-To: <CAL_JsqJwKQ_KuWWQNZHrMh8NwwiubB2jR+g-Y2n_dH4kJ5zVow@mail.gmail.com>
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
next prev parent reply other threads:[~2014-04-19 11:32 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-21 21:08 [PATCH 0/8] Generic serial earlycon Rob Herring
[not found] ` < 201403221054.39799.arnd@arndb.de>
[not found] ` < CAL_JsqKjGjyYypwneCmNc1qeKe0ZOG9gz3QSJ37-HwHXKu3iRA@mail.gmail.com>
[not found] ` < 20140329001732.BECE2C41FF4@trevor.secretlab.ca>
2014-03-21 21:08 ` [PATCH 1/8] x86: move FIX_EARLYCON_MEM kconfig into x86 Rob Herring
2014-03-21 21:08 ` [PATCH 2/8] arm64: add FIXMAP_PAGE_NOCACHE definition Rob Herring
2014-03-24 11:13 ` Catalin Marinas
2014-03-21 21:08 ` [PATCH 3/8] arm64: enable FIX_EARLYCON_MEM kconfig Rob Herring
2014-03-24 11:38 ` Catalin Marinas
2014-03-21 21:08 ` [PATCH 4/8] tty/serial: add generic serial earlycon Rob Herring
2014-03-24 11:22 ` Catalin Marinas
2014-03-24 11:29 ` Arnd Bergmann
2014-03-24 13:36 ` Rob Herring
2014-03-24 15:42 ` Arnd Bergmann
2014-04-17 18:27 ` Rob Herring
2014-04-17 20:16 ` Alan Cox
2014-04-19 11:32 ` Arnd Bergmann [this message]
2014-03-21 21:08 ` [PATCH 5/8] tty/serial: convert 8250 to generic earlycon Rob Herring
2014-03-21 21:08 ` [PATCH 6/8] tty/serial: pl011: add generic earlycon support Rob Herring
2014-03-24 11:28 ` Catalin Marinas
2014-04-16 22:14 ` Rob Herring
2014-04-23 16:39 ` Catalin Marinas
2014-03-21 21:08 ` [PATCH 7/8] tty/serial: add arm64 semihosting earlycon Rob Herring
2014-03-23 20:04 ` Nicolas Pitre
2014-03-23 20:23 ` Arnd Bergmann
2014-03-23 21:48 ` Nicolas Pitre
2014-03-24 11:38 ` Catalin Marinas
2014-03-24 11:48 ` Catalin Marinas
2014-03-21 21:08 ` [PATCH 8/8] arm64: remove arch specific earlyprintk Rob Herring
2014-03-22 9:54 ` [PATCH 0/8] Generic serial earlycon Arnd Bergmann
2014-03-22 14:14 ` Rob Herring
2014-03-22 22:01 ` Arnd Bergmann
2014-03-23 15:09 ` Rob Herring
2014-03-23 19:49 ` Arnd Bergmann
2014-03-29 0:17 ` Grant Likely
2014-03-29 14:33 ` Rob Herring
2014-03-29 15:34 ` Grant Likely
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