Date: Tue, 12 May 2015 10:52:53 +0200
From: Pavel Machek <pavel@ucw.cz>
To: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Tomi Valkeinen <tomi.valkeinen@ti.com>,
        Archit Taneja <architt@codeaurora.org>,
        Marek Vasut <marek.vasut@gmail.com>,
        kernel list <linux-kernel@vger.kernel.org>,
        Dinh Nguyen <dinh.linux@gmail.com>,
        Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>,
        Grant Likely <grant.likely@linaro.org>,
        Rob Herring <robh+dt@kernel.org>, Jingoo Han <jg1.han@samsung.com>,
        Rob Clark <robdclark@gmail.com>,
        Linux Fbdev development list <linux-fbdev@vger.kernel.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        Alexander Shiyan <shc_work@mail.ru>,
        H Hartley Sweeten <hsweeten@visionengravers.com>
Subject: Re: simple framebuffer slower by factor of 20, on socfpga (arm)
 platform
Message-ID: <20150512085253.GA4606@amd>
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 <CAMuHMdV+-VcZD5TMswUjwW0fk=-76oYimeKJ_P9QC5Md4De-JA@mail.gmail.com>
 <20150428134848.GC12732@n2100.arm.linux.org.uk>
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On Wed 2015-05-06 11:45:04, Russell King - ARM Linux wrote:
> On Tue, Apr 28, 2015 at 11:28:53AM -0400, Nicolas Pitre wrote:
> > On Tue, 28 Apr 2015, Russell King - ARM Linux wrote:
> > 
> > > On Fri, Apr 24, 2015 at 03:46:56PM +0200, Geert Uytterhoeven wrote:
> > > > So please optimize ARM's _memcpy_fromio(), _memcpy_toio(), and _memset_io().
> > > > That will benefit other drivers on ARM, too.
> > > 
> > > That's not going to happen.
> > > 
> > > I've had a patch which does that, but people are concerned that it changes
> > > the behaviour of the functions by changing the access size, which could
> > > cause regressions.  It seems people are far too worried about that to even
> > > consider trying. :(
> > 
> > What about making the optimized implementation available via kconfig?
> 
> I'd prefer not to.  My personal feeling is to put the patch in and just be
> done with it - these functions are supposed to be used on IO areas which
> don't care about access size (in other words, are memory-like rather than
> being register-like.)  Here's the rather old patch:
> 
> From: Russell King <rmk+kernel@arm.linux.org.uk>
> Subject: [PATCH] ARM: optimize memset_io()/memcpy_fromio()/memcpy_toio()
> 
> If we are building for a LE platform, and we haven't overriden the
> MMIO ops, then we can optimize the mem*io operations using the
> standard string functions.
> 
> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Tested-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Pavel Machek <pavel@ucw.cz>

Works for me, framebuffer performance is back in "too fast to measure"
range.

When this is merged, should 981409b25e2a99409b26daa67293ca1cfd5ea0a0
be reverted in -stable?

Thanks,
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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