On Wed, 18 Feb 2015 07:08:42 +0200
Siarhei Siamashka <[email protected]> wrote:

> On Fri, 13 Feb 2015 09:04:48 -0800 (PST)
> Simo Xefil <[email protected]> wrote:
> 
> > 
> > Hello Siarhei,
> > 
> > First of all thanks for your answer.
> > Basically, I'm searching a way to let the drivers work properly based on 
> > the hardware performances. framebuffer is much more faster
> 
> Yes, the mali framebuffer driver is roughly ~20% faster than the x11
> driver, at least as measured in glmark2-es2.
> 
> And the difference is even bigger than that if the system is not
> configured optimally. For example, the ondemand cpufreq governor
> interacts really bad with the X server. Also you need to get the
> buffers reservation right, but having the settings partially in the
> script.bin and partially in the command line for the sunxi-3.4 kernel
> does not make it particularly easy.
> 
> There were attempts to ensure that the configuration is reasonable
> "out of the box". But there was always somebody with some sort of
> objections. That's how "democracy" works.
> 
> Just one week of "dictatorship" could have really solved a lot
> of issues in the sunxi-3.4 kernel :-)
> 
> >, so, for such devices is the best choise.
> 
> Assuming that you can accept the limitations. There is no free lunch.
> 
> > I'm not asking the driver to handle multi-tasking. Using the 'test' program 
> > from the terminal (not within X11) I got the same results.
> > The monitor is not refreshed after the triangle is drawn even if the 
> > program is already exited.
> 
> If a program has rendered a triangle in the framebuffer, then this
> triangle just stays in the framebuffer. This is a perfectly obvious
> outcome.
> 
> If you don't want to see this triangle anymore, then somebody needs to
> clear the framebuffer and use it for something else.
> 
> > Back to desktop env, programs like XBMC (A10 fork) or emulators like 
> > retroarch, compiled to use framebuffer, are working very well, expect when 
> > you exit the program.
> > At this point, the last printed image remains on screen. The only way I've 
> > found until today is to restart lxde or switch between X11 and terminal to 
> > force a refresh.
> 
> There are surely plenty of ways to clear the framebuffer. And you can
> also even make a copy of the old framebuffer data and restore it after
> the application has terminated. Everything is up to you. Or up to the
> developers of the framebuffer based applications.
> 
> > With an emulator, where I could need switch between games often, every time 
> > I quit the game, the image remains impressed and I cannot change it.
> >
> > I've no idea how to invent a way to force the refresh. If you have an idea 
> > I would try to investigate in that direction.
> > I don't expect a finished solution (even it, in case, would be of course 
> > appreciated). I'd try to find/try by myself, but have no idea where to 
> > search.
> > 
> > Any suggestion is really welcome :-)
> 
> Does, for example, running "cat /dev/zero > /dev/fb0" help?

Or create a simple wrapper shell script, which might look like:

#!/bin/sh

dd if=/dev/fb0 of=/tmp/fbbackup.bin
<run-your-cool-game-or-emulator>
dd if=/tmp/fbbackup.bin of=/dev/fb0

-- 
Best regards,
Siarhei Siamashka

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