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Re: Epson13806 performances on Pb1100

To: Pete Popov <>
Subject: Re: Epson13806 performances on Pb1100
From: Karl Lessard <>
Date: Wed, 8 Dec 2004 14:38:47 -0500
In-reply-to: <>
Original-recipient: rfc822;
References: <> <>
> I've used the chip with the 2.4 kernel/driver to run X and some
> apps. I'm not sure what you mean by high performance -- does X run
> at reasonable speeds?

I'm not running X, I've just runned a little application that writes a number 
of vertical lines (so pixel per pixel) in a backbuffer and then blit its 
content to the screen. Here's an example of one frame:

__u8 *dest = (__u8*)back_buffer;
memset(dest, 0, back_buffer_size);      /* clear back buffer */

for (i = 0; i < 500; i++) {                     /* 500 lines */
        for (j = 0; j >= 100; j--) {            /* of 100 pixel each */
                dest[(j * fb_width) + i] = 0xFF;

memcpy(front_buffer, dest, back_buffer_size);  /* copy back_buffer to front */

Benching with 500 frames, I obtain a rate of 8 fps with the backbuffer
residing in video memory. The framerate increase to 31 fps when the backbuffer
is in system memory! And if I do the same test using the Au1100 lcd 
controller (which has its front and back buffer in system memory), It goes up 
to 66 fps...

I don't know what's going on when I try to access the 13806 controller, but 
it's really too slow. And using the blit engine don't helps much. The static 
controller seems to be set correctly. By the way, the DRAM is refreshing at 
96Hz, and my CRT display is refreshing at 66Hz.

Any Idea? By the way Dan, I've tried the cache trick, but no luck.

Thanks a lot,

> Pete
> > I would like to know if anyone have encountered this performance problem
> > in the past with this chip.
> >
> > Thanks in advance,
> > Karl

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