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?

-- 
Best regards,
Siarhei Siamashka

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