From: arnd@arndb•de (Arnd Bergmann)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 02/08] ARM: shmobile: Rework SH73A0_SCU_BASE IOMEM() usage
Date: Mon, 18 Feb 2013 14:44:21 +0000 [thread overview]
Message-ID: <201302181444.21717.arnd@arndb.de> (raw)
In-Reply-To: <201302181439.08639.arnd@arndb.de>
On Monday 18 February 2013, Arnd Bergmann wrote:
> Ok, this gets rid of the warning, but I'm a bit worried about
> how it is hardwiring the fact that the SCU physical address has
> the same bit pattern as the __iomem token.
>
> While I realize that you already rely on this in a lot of places
> in the shmobile code, I see a red light going off every time I read
> code like this, and it is not any more logical than the previous
> version.
>
> It would be nice to keep these address spaces separate at least
> in new code, mostly in order to not confuse reviewers with code
> that is based on assumptions which are not generally true, but also
> to be more flexible with the virtual memory layout. On a related
> topic, you are using an entire 256 MB section of your virtual
> address space for sh73a0 and sh7372 and 160 MB for r8a7740. Putting
> less of that into the identity mapped area would free up space for
> vmalloc, but it's hard to prove that doing this is correct when
> you have all sorts of code using a hardcoded virtual MMIO address
> token.
To clarify my rant: I'm absolutely fine with this code going in
for now, but I'd like to see a long-term plan about what to do
with the hardcoded virtual address hacks.
Arnd
next prev parent reply other threads:[~2013-02-18 14:44 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-18 13:46 [PATCH 00/08] ARM: shmobile: CPU Hotplug and SMP CA9 SCU rework part 2 Magnus Damm
2013-02-18 13:46 ` [PATCH 01/08] ARM: shmobile: Fix base address readout in headsmp-scu.S Magnus Damm
2013-02-18 14:57 ` Bastian Hecht
2013-02-18 13:47 ` [PATCH 02/08] ARM: shmobile: Rework SH73A0_SCU_BASE IOMEM() usage Magnus Damm
2013-02-18 14:39 ` Arnd Bergmann
2013-02-18 14:44 ` Arnd Bergmann [this message]
2013-02-25 14:30 ` Magnus Damm
2013-02-26 10:18 ` Arnd Bergmann
2013-02-26 15:20 ` Magnus Damm
2013-02-26 16:12 ` Arnd Bergmann
2013-03-06 7:15 ` Magnus Damm
2013-02-18 13:47 ` [PATCH 03/08] ARM: shmobile: Use R8A7779_SCU_BASE with TWD Magnus Damm
2013-02-18 13:47 ` [PATCH 04/08] ARM: shmobile: Update r8a7779 to check SCU for hotplug Magnus Damm
2013-02-18 13:47 ` [PATCH 05/08] ARM: shmobile: Update r8a7779 to use scu_power_mode() Magnus Damm
2013-02-18 13:47 ` [PATCH 06/08] ARM: shmobile: Use sh73a0-specific cpu disable code Magnus Damm
2013-02-18 13:47 ` [PATCH 07/08] ARM: shmobile: Rearrange r8a7779 cpu hotplug code Magnus Damm
2013-02-18 13:48 ` [PATCH 08/08] ARM: shmobile: Remove unused hotplug.c Magnus Damm
2013-02-19 0:49 ` [PATCH 00/08] ARM: shmobile: CPU Hotplug and SMP CA9 SCU rework part 2 Simon Horman
2013-02-19 10:09 ` Magnus Damm
2013-02-26 8:53 ` Simon Horman
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