Date: Fri, 24 Apr 2015 15:31:24 +0200
From: Pavel Machek <pavel@ucw.cz>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>,
        Geert Uytterhoeven <geert@linux-m68k.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>,
        shc_work@mail.ru, linux@arm.linux.org.uk, hsweeten@visionengravers.com,
        Archit Taneja <architt@codeaurora.org>
Subject: Re: simple framebuffer slower by factor of 20, on socfpga (arm)
 platform
Message-ID: <20150424133124.GB11729@amd>
References: <20150407121247.GA29497@amd>
 <552660C7.4020805@ti.com>
 <552663C2.70308@ti.com>
 <2137270.OOdtDiT2H4@wuerfel>
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> > The difference is probably caused by memcpy() vs memcpy_fromio(). The
> > comment above memcpy_fromio() says "This needs to be optimized". I think
> > generally speaking memcpy_fromio() is correct for a framebuffer.
> > 
> > That said, if the fb is in RAM, and is only written by the CPU, I think
> > a normal memcpy() for fb_memcpy_fromfb() should be fine...
> 
> Could memcpy() cause alignment traps here if the fb pointer is unaligned
> and uncached?

Original commit did not comment on any failure, so I expect that is
not a problem here...
									Pavel
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