From: Arnd Bergmann <arnd@arndb.de>
To: linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] fb.h: ARM uses __raw_{read/write}
Date: Mon, 13 Jun 2011 13:37:10 +0000 [thread overview]
Message-ID: <201106131537.10698.arnd@arndb.de> (raw)
In-Reply-To: <20110613100819.GA26914@1n450.cable.virginmedia.net>
On Monday 13 June 2011 12:08:19 Catalin Marinas wrote:
> The change proposed by Hartley wouldn't make much difference from the
> current volatile accesses (__raw_* accessors are implemented as volatile
> on ARM).
I guess it would mainly make a difference if we get a platform where
the PCI bus window is not in the same address space as the regular
physical memory and the accessors actually need to do a computation
on the address. AFAICT, ARM does not currently have any such platform
and I would hope that it says that way.
> I think the memcpy_(from|to)io could be optimised on ARM to only add a
> barrier before or after he copying loop.
Agreed, good idea.
Arnd
WARNING: multiple messages have this Message-ID (diff)
From: arnd@arndb.de (Arnd Bergmann)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] fb.h: ARM uses __raw_{read/write}
Date: Mon, 13 Jun 2011 15:37:10 +0200 [thread overview]
Message-ID: <201106131537.10698.arnd@arndb.de> (raw)
In-Reply-To: <20110613100819.GA26914@1n450.cable.virginmedia.net>
On Monday 13 June 2011 12:08:19 Catalin Marinas wrote:
> The change proposed by Hartley wouldn't make much difference from the
> current volatile accesses (__raw_* accessors are implemented as volatile
> on ARM).
I guess it would mainly make a difference if we get a platform where
the PCI bus window is not in the same address space as the regular
physical memory and the accessors actually need to do a computation
on the address. AFAICT, ARM does not currently have any such platform
and I would hope that it says that way.
> I think the memcpy_(from|to)io could be optimised on ARM to only add a
> barrier before or after he copying loop.
Agreed, good idea.
Arnd
WARNING: multiple messages have this Message-ID (diff)
From: Arnd Bergmann <arnd@arndb.de>
To: linux-arm-kernel@lists.infradead.org
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Paul Mundt <lethal@linux-sh.org>,
H Hartley Sweeten <hartleys@visionengravers.com>,
Russell King <linux@arm.linux.org.uk>,
Linux Kernel <linux-kernel@vger.kernel.org>,
linux-fbdev@vger.kernel.org
Subject: Re: [PATCH] fb.h: ARM uses __raw_{read/write}
Date: Mon, 13 Jun 2011 15:37:10 +0200 [thread overview]
Message-ID: <201106131537.10698.arnd@arndb.de> (raw)
In-Reply-To: <20110613100819.GA26914@1n450.cable.virginmedia.net>
On Monday 13 June 2011 12:08:19 Catalin Marinas wrote:
> The change proposed by Hartley wouldn't make much difference from the
> current volatile accesses (__raw_* accessors are implemented as volatile
> on ARM).
I guess it would mainly make a difference if we get a platform where
the PCI bus window is not in the same address space as the regular
physical memory and the accessors actually need to do a computation
on the address. AFAICT, ARM does not currently have any such platform
and I would hope that it says that way.
> I think the memcpy_(from|to)io could be optimised on ARM to only add a
> barrier before or after he copying loop.
Agreed, good idea.
Arnd
next prev parent reply other threads:[~2011-06-13 13:37 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-11 0:31 [PATCH] fb.h: ARM uses __raw_{read/write} H Hartley Sweeten
2011-06-11 0:31 ` H Hartley Sweeten
2011-06-11 0:31 ` H Hartley Sweeten
2011-06-13 4:00 ` Paul Mundt
2011-06-13 4:00 ` Paul Mundt
2011-06-13 4:00 ` Paul Mundt
2011-06-13 10:08 ` Catalin Marinas
2011-06-13 10:08 ` Catalin Marinas
2011-06-13 10:08 ` Catalin Marinas
2011-06-13 13:37 ` Arnd Bergmann [this message]
2011-06-13 13:37 ` Arnd Bergmann
2011-06-13 13:37 ` Arnd Bergmann
2011-06-13 13:57 ` Russell King - ARM Linux
2011-06-13 13:57 ` Russell King - ARM Linux
2011-06-13 13:57 ` Russell King - ARM Linux
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