[uClinux-dev] framebuffer/console question

Angelo Dureghello angelo70 at gmail.com
Sat Sep 22 17:38:38 EDT 2012


Hi Geert,

well, i finally have it working.

I had to set some values inside my fb driver to see the fonts:

static struct fb_fix_screeninfo amcorefb_fix __initdata = {
	.id             = "amcorefb",
	.type           = FB_TYPE_PACKED_PIXELS,
	.visual         = FB_VISUAL_MONO10,
	.xpanstep       = 0,
	.ypanstep       = 1,
	.ywrapstep      = 0,
	.accel          = FB_ACCEL_NONE,
	.line_length    = (128/8),
};

static struct fb_var_screeninfo amcorefb_var __initdata = {
	.xres           = 128,
	.yres           = 64,
	.xres_virtual   = 128,
	.yres_virtual   = 64,
	.bits_per_pixel = 1,
	.nonstd         = 1,
};

and also

info->var.red.offset = 0;
info->var.red.length = info->var.bits_per_pixel;
info->var.green = info->var.red;
info->var.blue  = info->var.red;

inside probe function. As above, RGB structs values must be initialized, otherwise nothing is displayed.


I still have a problem. Every single fonts is now displayed mirrored to left. But entire text go left to right correctly. Seems to be a "bit" endiannes issue inside a byte. This should be easy to solve.

Thanks again
angelo





On 20/09/2012 21:19, Geert Uytterhoeven wrote:
> Hi Angelo,
> 
> On Mon, Sep 17, 2012 at 2:29 PM, angelo <angelo70 at gmail.com> wrote:
>> i have a working coldfire board, running uClinux. I connected a 128x64
>> monochrome lcd on gpio, and written a framebuffer driver.
> 
> On gpio, so it's not memory mapped?
> 
>> From userspace i can now write on "/dev/fb0" and see some images properly.
> 
> Good.
> 
>> My question now is about console. Just for playing, i am trying to see the
>> console output on the LCD. Even if very small, this should be possible, as i
>> enabled the "console framebuffer" driver and some fonts.
> 
> OK.
> 
>> Once i booted linux, i try an echo "test" > /dev/console, something seems to
>> happen on the screen, some pixels are cleared, but i don't see nothing
>> similar to font chars.
> 
> Strange.
> 
>> I read fb and fbcon docs, but i couldn't find any document that explain if
>> console fb driver (fbcon) can be used with some fb drivers only (like
>> vesfb), or with any fb driver. So my question is: is it possible or i should
>> add/create some additional driver ?
> 
> The console should work, assumed you provided the proper drawing operations
> in your struct fb_ops. E.g. for simple packed monochrome:
> 
>         .fb_fillrect            = cfb_fillrect,
>         .fb_copyarea            = cfb_copyarea,
>         .fb_imageblit           = cfb_imageblit,
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds




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