From mboxrd@z Thu Jan  1 00:00:00 1970
From: Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>
Subject: Re: [PATCH 4/7] io-64-nonatomic: Add relaxed accessor variants
Date: Mon, 25 Apr 2016 17:21:34 +0200
Message-ID: <5485134.l18Z1dlVmn@wuerfel>
References: <cover.1460391217.git.robin.murphy@arm.com>
	<571A5A9E.7040305@arm.com> <20160425133242.GC30830@arm.com>
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To: Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>
Cc: Hitoshi Mitake <mitake.hitoshi-Zyj7fXuS5i5L9jVzuh4AOg@public.gmane.org>, Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, tchalamarla-M3mlKVOIwJVv6pq1l3V1OdBPR1lH4CV8@public.gmane.org, brian.starkey-5wv7dgnIgG8@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Darren Hart <dvhart-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
List-Id: iommu@lists.linux-foundation.org

On Monday 25 April 2016 14:32:42 Will Deacon wrote:
> > >>
> > >>+static inline __u64 hi_lo_readq_relaxed(const volatile void __iomem *addr)
> > >>+{
> > >>+   const volatile u32 __iomem *p = addr;
> > >>+   u32 low, high;
> > >>+
> > >>+   high = readl_relaxed(p + 1);
> > >>+   low = readl_relaxed(p);
> > >>+
> > >>+   return low + ((u64)high << 32);
> > >>+}
> > >>+
> > >>+static inline void hi_lo_writeq_relaxed(__u64 val, volatile void __iomem *addr)
> > >>+{
> > >>+   writel_relaxed(val >> 32, addr + 4);
> > >>+   writel_relaxed(val, addr);
> > >>+}
> > >
> > >Could we not generate the _relaxed variants with some macro magic?
> > 
> > We _could_ - indeed I started doing that, but then decided that the
> > obfuscation of horrible macro-templated functions wasn't worth saving a
> > couple of hundred bytes in some code that isn't exactly difficult to
> > maintain and has needed touching once in 4 years.
> > 
> > If you did want to go down the macro route, I may as well also generate both
> > lo-hi and hi-lo headers all from a single template, it'd be really clever...
> > <alarm bells> 
> 
> I certainly wasn't suggesting any more than the obvious macroisation,
> but I'll leave it up to Arnd, as I think this falls on his lap.

I'd prefer the open-coded variant as well.

	Arnd