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From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Arnd Bergmann <arnd@arndb.de>
Cc: linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, Will Deacon <will.deacon@arm.com>,
	Nicolas Pitre <nico@linaro.org>,
	"James E.J. Bottomley" <JBottomley@parallels.com>,
	linux-scsi@vger.kernel.org
Subject: Re: [PATCH 22/24] scsi: eesox: use __iomem pointers for MMIO
Date: Sat, 15 Sep 2012 09:57:34 +0100	[thread overview]
Message-ID: <20120915085734.GG12245@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <201209150800.35605.arnd@arndb.de>

On Sat, Sep 15, 2012 at 08:00:35AM +0000, Arnd Bergmann wrote:
> On Friday 14 September 2012, Russell King - ARM Linux wrote:
> > On Fri, Sep 14, 2012 at 11:34:50PM +0200, Arnd Bergmann wrote:
> > > ARM is moving to stricter checks on readl/write functions,
> > > so we need to use the correct types everywhere.
> > 
> > There's nothing wrong with const iomem pointers.  If you think
> > otherwise, patch x86 not to use const in its accessor implementation
> > and watch the reaction:
> > 
> > #define build_mmio_read(name, size, type, reg, barrier) \
> > static inline type name(const volatile void __iomem *addr) \
> > { type ret; asm volatile("mov" size " %1,%0":reg (ret) \
> > :"m" (*(volatile type __force *)addr) barrier); return ret; }
> > 
> > build_mmio_read(readb, "b", unsigned char, "=q", :"memory")
> > build_mmio_read(readw, "w", unsigned short, "=r", :"memory")
> > build_mmio_read(readl, "l", unsigned int, "=r", :"memory")
> 
> Ok, fair enough. Can you fold the patch below into 
> "ARM: 7500/1: io: avoid writeback addressing modes for __raw_
> accessors", or apply on top then?

No - const is not appropriate for the write accessors.  Again, this puts
us at odds with x86:

#define build_mmio_write(name, size, type, reg, barrier) \
static inline void name(type val, volatile void __iomem *addr) \
{ asm volatile("mov" size " %0,%1": :reg (val), \
"m" (*(volatile type __force *)addr) barrier); }

build_mmio_write(writeb, "b", unsigned char, "q", :"memory")
build_mmio_write(writew, "w", unsigned short, "r", :"memory")
build_mmio_write(writel, "l", unsigned int, "r", :"memory")

So, readl etc are all const volatile void __iomem *, but writel etc are
all volatile void __iomem *.

How they're defined on ARM after 7500/1 copies how they're defined on
x86.

  reply	other threads:[~2012-09-15  8:57 UTC|newest]

Thread overview: 71+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1347658492-11608-1-git-send-email-arnd@arndb.de>
2012-09-14 21:34 ` [PATCH 01/24] ARM: shmobile: use __iomem pointers for MMIO Arnd Bergmann
2012-09-18  7:11   ` Simon Horman
2012-09-18  8:31     ` Arnd Bergmann
2012-09-18 11:50       ` Simon Horman
2012-09-18 16:04         ` Arnd Bergmann
2012-09-18 23:56           ` Simon Horman
2012-09-18  7:42   ` Paul Mundt
2012-09-14 21:34 ` [PATCH 02/24] ARM: at91: " Arnd Bergmann
2012-09-17  7:56   ` Nicolas Ferre
2012-09-18  8:05     ` Arnd Bergmann
2012-09-14 21:34 ` [PATCH 03/24] ARM: ebsa110: " Arnd Bergmann
2012-09-14 21:34 ` [PATCH 04/24] ARM: ep93xx: " Arnd Bergmann
2012-09-14 22:14   ` Ryan Mallon
2012-09-15  7:55     ` Arnd Bergmann
2012-09-14 21:34 ` [PATCH 05/24] ARM: imx: " Arnd Bergmann
2012-09-14 22:31   ` Fabio Estevam
2012-09-15 17:42     ` Arnd Bergmann
2012-09-16  7:21       ` Sascha Hauer
2012-09-14 21:34 ` [PATCH 06/24] ARM: integrator: " Arnd Bergmann
2012-09-16 22:19   ` Linus Walleij
2012-09-16 22:35     ` Russell King - ARM Linux
2012-09-16 22:46       ` Linus Walleij
2012-09-16 23:43         ` Russell King - ARM Linux
2012-09-14 21:34 ` [PATCH 07/24] ARM: iop13xx: " Arnd Bergmann
2012-09-14 21:34 ` [PATCH 08/24] ARM: iop32x: " Arnd Bergmann
2012-09-14 21:34 ` [PATCH 09/24] ARM: ixp4xx: " Arnd Bergmann
2012-09-18 10:31   ` Krzysztof Halasa
2012-09-18 19:22     ` Krzysztof Halasa
2012-09-19 13:52       ` Arnd Bergmann
2012-09-18 20:12   ` [PATCH 08+09/24] " Krzysztof Halasa
2012-09-18 21:25     ` Arnd Bergmann
2012-09-14 21:34 ` [PATCH 10/24] ARM: ks8695: " Arnd Bergmann
2012-09-14 21:34 ` [PATCH 11/24] ARM: lpc32xx: " Arnd Bergmann
2012-09-14 21:34 ` [PATCH 12/24] ARM: msm: " Arnd Bergmann
2012-09-14 22:38   ` Stephen Boyd
2012-09-15  5:16     ` David Brown
2012-09-14 21:34 ` [PATCH 13/24] ARM: nomadik: " Arnd Bergmann
2012-09-16 22:24   ` Linus Walleij
2012-09-14 21:34 ` [PATCH 14/24] ARM: prima2: " Arnd Bergmann
2012-09-14 21:34 ` [PATCH 15/24] ARM: sa1100: " Arnd Bergmann
2012-09-14 21:34 ` [PATCH 16/24] ARM: spear13xx: " Arnd Bergmann
2012-09-14 21:34 ` [PATCH 17/24] ARM: OMAP: " Arnd Bergmann
2012-09-15 18:10   ` Tony Lindgren
2012-09-15 20:14     ` Arnd Bergmann
2012-09-16 20:38       ` Tony Lindgren
2012-09-17 21:25         ` Tony Lindgren
2012-09-19 13:35           ` Arnd Bergmann
2012-09-19 13:36             ` Felipe Balbi
2012-09-19 16:44               ` Tony Lindgren
2012-09-14 21:34 ` [PATCH 18/24] ARM: samsung: " Arnd Bergmann
2012-09-14 21:34 ` [PATCH 19/24] sh: " Arnd Bergmann
2012-09-18  7:37   ` Paul Mundt
2012-09-18  8:01     ` Arnd Bergmann
2012-09-14 21:34 ` [PATCH 20/24] input: rpcmouse: " Arnd Bergmann
2012-09-19 17:06   ` Dmitry Torokhov
2012-09-14 21:34 ` [PATCH 21/24] serial: ks8695: " Arnd Bergmann
2012-09-14 23:44   ` Greg Kroah-Hartman
2012-09-14 21:34 ` [PATCH 22/24] scsi: eesox: " Arnd Bergmann
2012-09-14 23:27   ` Russell King - ARM Linux
2012-09-15  8:00     ` Arnd Bergmann
2012-09-15  8:57       ` Russell King - ARM Linux [this message]
2012-09-15 10:30         ` Arnd Bergmann
2012-09-17 22:03           ` Russell King - ARM Linux
2012-09-18  8:09             ` Arnd Bergmann
2012-09-14 21:34 ` [PATCH 23/24] video: da8xx-fb: " Arnd Bergmann
2012-09-14 21:34 ` [PATCH 24/24] net: seeq: " Arnd Bergmann
2012-09-14 23:56   ` Russell King - ARM Linux
2012-09-15  4:00     ` David Miller
2012-09-18  8:14       ` Arnd Bergmann
2012-09-15 11:33 ` [PATCH 13/24] ARM: nomadik: " Alessandro Rubini
2012-09-28 20:13   ` Arnd Bergmann

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