From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Date: Fri, 24 Apr 2015 13:31:24 +0000 Subject: Re: simple framebuffer slower by factor of 20, on socfpga (arm) platform Message-Id: <20150424133124.GB11729@amd> List-Id: References: <20150407121247.GA29497@amd> <552660C7.4020805@ti.com> <552663C2.70308@ti.com> <2137270.OOdtDiT2H4@wuerfel> In-Reply-To: <2137270.OOdtDiT2H4@wuerfel> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Arnd Bergmann Cc: Tomi Valkeinen , Geert Uytterhoeven , Marek Vasut , kernel list , Dinh Nguyen , Jean-Christophe PLAGNIOL-VILLARD , Grant Likely , Rob Herring , Jingoo Han , Rob Clark , Linux Fbdev development list , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , shc_work-JGs/UdohzUI@public.gmane.org, linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org, hsweeten-3FF4nKcrg1dE2c76skzGb0EOCMrvLtNR@public.gmane.org, Archit Taneja > > 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 -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html