why does the lcd display so lag.

       we are using H7202 an Arm7 chip(70MHz) to run linux. When we use
X with LCD whose resolution is 640*480 and 8 bit depth, it is too lag
to run smoothly.
       would it be better when we use 320*240 resolution? how would i
change the resolution? i used fbset to set xres and yres to 320 and 240
seperately, a quarter of display is working. that's not what i wanted.
       Any help would be apprieciated.

Archer <xydarcher@163.com> wrote:

>        we are using H7202 an Arm7 chip(70MHz) to run linux. When we
> use X with LCD whose resolution is 640*480 and 8 bit depth, it is
> too lag to run smoothly.

Which "it" is that: the CPU, the X server, or the LCD?  And how
sluggish is it, actually?

-- 
Hans-Bernhard Broeker (broeker@physik.rwth-aachen.de)
Even if all the snow were burnt, ashes would remain.

> a quarter of display is working. that's not what i wanted.

Is that quarter running any quicker? 

no it seems that it's the same with full screen.
Tom Lucas wrote:
> > a quarter of display is working. that's not what i wanted.
> 
> Is that quarter running any quicker?

    It means the picture of display. The picture appeared very slow. It
will twinkle when we change some text content dynamicly.

Hans-Bernhard Broeker wrote:
> Archer <xydarcher@163.com> wrote:
>
> >        we are using H7202 an Arm7 chip(70MHz) to run linux. When we
> > use X with LCD whose resolution is 640*480 and 8 bit depth, it is
> > too lag to run smoothly.
>
> Which "it" is that: the CPU, the X server, or the LCD?  And how
> sluggish is it, actually?
>
> --
> Hans-Bernhard Broeker (broeker@physik.rwth-aachen.de)
> Even if all the snow were burnt, ashes would remain.

Archer <xydarcher@163.com> wrote:
> Hans-Bernhard Broeker wrote:
> > Archer <xydarcher@163.com> wrote:

> > >        we are using H7202 an Arm7 chip(70MHz) to run linux. When we
> > > use X with LCD whose resolution is 640*480 and 8 bit depth, it is
> > > too lag to run smoothly.

> > Which "it" is that: the CPU, the X server, or the LCD?  And how
> > sluggish is it, actually?

>     It means the picture of display. The picture appeared very slow. It
> will twinkle when we change some text content dynamicly.

[Please don't top-post.  Fixed.]

So basically, it means you have no idea where the bottleneck is.
You only know that by the time the contents arrive on the screen,
they're too late.

But how on earth could "to twinkle" apply to an LCD screen?  I don't
think that term has any recognized meaning other than those applied to
stars in the sky, and maybe to jewels.

Anyway, text output may not be the best test case here.  Text output
over a graphical display pipeline like X11 involves considerable work,
which often has to be done by software.  Try whooshing a small
graphical object (a short line, maybe even a single dot) around,
instead.

What kind of LCD controller do you use?  Does it have any kind of
hardware support for drawing of 2D graphics primitives?  If so, is
there a proper X server for it, or are you relying on the framebuffer
server?

-- 
Hans-Bernhard Broeker (broeker@physik.rwth-aachen.de)
Even if all the snow were burnt, ashes would remain.

Hans-Bernhard Broeker wrote:
>
> [Please don't top-post.  Fixed.]
>
> So basically, it means you have no idea where the bottleneck is.
> You only know that by the time the contents arrive on the screen,
> they're too late.
>
> But how on earth could "to twinkle" apply to an LCD screen?  I don't
> think that term has any recognized meaning other than those applied to
> stars in the sky, and maybe to jewels.
>
> Anyway, text output may not be the best test case here.  Text output
> over a graphical display pipeline like X11 involves considerable work,
> which often has to be done by software.  Try whooshing a small
> graphical object (a short line, maybe even a single dot) around,
> instead.
we need a stable text out function. so text experiment is applied.
>
> What kind of LCD controller do you use?  Does it have any kind of
> hardware support for drawing of 2D graphics primitives?  If so, is
> there a proper X server for it, or are you relying on the framebuffer
> server?
>
Hynix H7202 contains a module for LCD controlling. It support the
framebuffer.
we are using miniGUI as our graphics engine.
> --
> Hans-Bernhard Broeker (broeker@physik.rwth-aachen.de)
> Even if all the snow were burnt, ashes would remain.