[okl4-developer] Is there any double buffering? S3C2410 lcd - FB

[Dennis Gessner]

Hi,

first of all, thank you Geoffrey, your hint with
"enable_fastpaths=False" solved the "clz" problems inside traps.spp. If
I find some time, I'll rewrite (patch) the traps.spp without all the
clz-instructions (which are not supported inside the ARMv4 architecture
of the S3C2410).

Now the kernel (okl4 2.1.1 patch 9) compiles and runs again on my real
hardware (gta01). What surprises me, it's not working inside qemu
(segmentation fault) - maybe there is something wrong with qemu...

Now my problem:

I am wondering if there is anything like double buffering inside the
lcd-output (fb) of the device. I initialize the lcd correctly, I get an
LCD-Mode returned (480x640 at 10).. I write
values to the fb, but the display is still black.

I am missing some command like "fb_refresh()" or anything that tells
okl4 that it should repaint the framebuffer with the new values.
Otherwise I do not understand why my display still stays black.

Here is what I did:

...
static int init_fb(struct ig_fb * fb, struct ig_lcd * lcd) {

    struct lcd_control_block *ctrl = lcd->control;
    fb->size = ctrl->xres * ctrl->yres * ctrl->bpp / 8;

    fb->ms = memsection_create_dma
	     (
	        fb->size,
	    	&fb->vbase,
	    	&fb->pm,
	    	L4_WriteThroughMemory
	      );

    virtual_lcd_set_fb(lcd->server, lcd->obj, fb->vbase, NULL);

    return 0;
}

static int write_to_fb(struct ig_fb * fb, struct ig_lcd * lcd) {

    int x, y, i = 0;
    char r, g, b;

    uintptr_t	fb_base;
    struct lcd_control_block *ctrl = lcd->control;

    uint16_t col;

    virtual_lcd_get_fb(lcd->server, lcd->obj, &fb_base, NULL);
    virtual_lcd_get_mode(lcd->server, lcd->obj, 				
&ctrl->xres,&ctrl->yres,&ctrl->bpp, NULL);

    uint16_t *fbp = (uint16_t*) fb_base;

    printf("xx  LCD Mode is %ldx%ld@%lx\n", lcd->control->xres,
           lcd->control->yres,lcd->control->bpp);

    printf("\nLeading 15 values of the fb: \n\n");
    for (i=0; i < 15; i++) {
	printf("%d--",fbp[i]);
    }

    i = 0;
	
    printf("\n...fill the fb...\n");
    for (x=0; x < ctrl->yres; x++) {
        for (y = 0; y < (ctrl->xres); y++) {

	    r = (x<y)?0:255;
	    g = (x<(ctrl->xres/2))?0:255;
	    b = (y<(ctrl->yres/2))?0:255;

	    col = (r&0x1f)      |
	          ((g&0x3f)<<5) |
		  ((b&0x1f)<<11);

            /* I also tried to manually set all values to 1024 */
// 	    fbp[i++] = 1024;

	    fbp[i++] = col;
        }
    }

    printf("\nLeading 15 values of the fb: \n\n");
    for (i=0; i < 15; i++) {
	printf("%d--",fbp[i]);
    }	
    printf("\n");

    /* I also tried the following, but this leads to a crash of 		
 okl4
    */
//    fb_base = (uintptr_t) fbp;
//    virtual_lcd_set_fb(lcd->server, lcd->obj, &fb_base, NULL);

    return 0;
}

What am I doing wrong?

Best regards,
Dennis