From: arnd@arndb•de (Arnd Bergmann)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v10 2/7] ARM: hi3xxx: add board support with device tree
Date: Wed, 16 Oct 2013 09:27:27 +0200 [thread overview]
Message-ID: <201310160927.27412.arnd@arndb.de> (raw)
In-Reply-To: <CAD6h2NQ4fT7ycmxh+iLiBx4+u6+QB-H98309cRJLtRO3LGCbJg@mail.gmail.com>
On Wednesday 16 October 2013, Haojian Zhuang wrote:
> Oh, no. I shouldn't extend the static mapping table to the entire range.
>
> Most of the registers only need to map once in the probe() function
> of the driver. Whether it's using static mapping or dynamic mapping,
> there's no difference.
There is a small difference in that having a megabyte-sized mapping will
reduce the number of TLB entries required for I/O access, which can
improve performance slightly. Other platforms do it for this reason.
> The sysctrl register bank is used in both clock & platform
> driver. Each clock node contains reg property, it needs to be parsed
> by of_iomap(). Hotplug & SMP platform driver needs to parse sysctrl
> register bank also. If I don't choose the static IO mapping for sysctrl
> register bank, I have to define some global variable to store the
> virtual address mapping. Or I have to cost lots of redundant virtual
> address space for the same IO mapping.
It's a small cost, but your approach makes sense, just make sure
you have a comment in the map_io code explaining it.
> So I'll only keep the static IO mapping for sysctrl.
I'd still choose the larger mapping, but I'll leave the decision to you.
Arnd
next prev parent reply other threads:[~2013-10-16 7:27 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-15 9:16 [PATCH v10 0/7] enable hi3xxx SoC Haojian Zhuang
2013-10-15 9:16 ` [PATCH v10 1/7] clk: hi3xxx: add clock support Haojian Zhuang
2013-10-30 19:44 ` Mike Turquette
2013-10-15 9:16 ` [PATCH v10 2/7] ARM: hi3xxx: add board support with device tree Haojian Zhuang
2013-10-15 13:00 ` Arnd Bergmann
2013-10-15 13:12 ` Haojian Zhuang
2013-10-15 18:06 ` Arnd Bergmann
2013-10-16 1:08 ` Haojian Zhuang
2013-10-16 1:31 ` Haojian Zhuang
2013-10-16 7:27 ` Arnd Bergmann [this message]
2013-10-15 9:16 ` [PATCH v10 3/7] ARM: dts: enable hi4511 " Haojian Zhuang
2013-10-15 18:18 ` Arnd Bergmann
2013-10-16 2:09 ` Haojian Zhuang
2013-10-16 7:10 ` Arnd Bergmann
2013-10-16 7:26 ` Linus Walleij
2013-10-15 9:16 ` [PATCH v10 4/7] ARM: config: enable hi3xxx in multi_v7_defconfig Haojian Zhuang
2013-10-15 9:16 ` [PATCH v10 5/7] ARM: config: add defconfig for Hi3xxx Haojian Zhuang
2013-10-15 9:16 ` [PATCH v10 6/7] ARM: hi3xxx: add smp support Haojian Zhuang
2013-10-15 9:16 ` [PATCH v10 7/7] ARM: hi3xxx: add hotplug support Haojian Zhuang
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