From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Date: Tue, 07 Apr 2015 12:12:47 +0000 Subject: simple framebuffer slower by factor of 20, on socfpga (arm) platform Message-Id: <20150407121247.GA29497@amd> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Marek Vasut , kernel list , dinh.linux@gmail.com Cc: plagnioj@jcrosoft.com, tomi.valkeinen@ti.com, grant.likely@linaro.org, robh+dt@kernel.org, jg1.han@samsung.com, robdclark@gmail.com, geert@linux-m68k.org, linux-fbdev@vger.kernel.org, devicetree@vger.kernel.org Hi! I have an socfpga board, which uses has simple framebuffer implemented in the FPGA. On 3.15, framebuffer is fast: root@wagabuibui:~# time cat /dev/fb0 > /dev/null real 0m 0.00s user 0m 0.00s sys 0m 0.00s on 3.18, this takes 220msec. Similar slowdown exists for writes. Simple framebuffer did not change at all between 3.15 and 3.18; resource flags of the framebuffer are still same (0x200). If I enable caching on 3.18, it speeds up a bit, to 70msec or so... Which means problem is not only in caching. Any ideas? Best regards, Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html