[uClinux-dev] framebuffer/console question

Angelo Dureghello angelo70 at gmail.com
Fri Sep 21 18:47:27 EDT 2012


Hi Geert,

thanks for your help.

For now the LCD is mapped on the parallel port PP0/PP16.

Yes, everytime i draw from userspace using "write" on /dev/fb i correctly see the image.
Same if i "echo somegarbage > /dev/fb" i can see some pixel drawn correctly.

The three functions in fb_opts are there, mapped and implemented. 

Still, nothing on the lcd on boot.
If i "echo something > /dev/console" i see part of the first line of pixels cleared.

This is my boot line
CONFIG_BOOTPARAM_STRING="root=/dev/mtdblock3 rootfstype=romfs init=/bin/init video=amcorefb console=tty0"

Some related configs

# 
# Frame buffer hardware drivers
#
CONFIG_FB_AMCORE=y

#
# Graphics support
#
# CONFIG_VGASTATE is not set
CONFIG_VIDEO_OUTPUT_CONTROL=y
CONFIG_FB=y
# CONFIG_FIRMWARE_EDID is not set
# CONFIG_FB_DDC is not set
# CONFIG_FB_BOOT_VESA_SUPPORT is not set
# CONFIG_FB_CFB_FILLRECT is not set
# CONFIG_FB_CFB_COPYAREA is not set
# CONFIG_FB_CFB_IMAGEBLIT is not set
# CONFIG_FB_CFB_REV_PIXELS_IN_BYTE is not set
CONFIG_FB_SYS_FILLRECT=y
CONFIG_FB_SYS_COPYAREA=y
CONFIG_FB_SYS_IMAGEBLIT=y
# CONFIG_FB_FOREIGN_ENDIAN is not set
# CONFIG_FB_SYS_FOPS is not set
# CONFIG_FB_SVGALIB is not set
# CONFIG_FB_MACMODES is not set
# CONFIG_FB_BACKLIGHT is not set
# CONFIG_FB_MODE_HELPERS is not set
# CONFIG_FB_TILEBLITTING is not set

#
# Character devices
#
CONFIG_VT=y
CONFIG_CONSOLE_TRANSLATIONS=y
CONFIG_VT_CONSOLE=y
CONFIG_HW_CONSOLE=y
CONFIG_VT_HW_CONSOLE_BINDING=y
# CONFIG_DEVKMEM is not set
# CONFIG_SERIAL_NONSTANDARD is not set
# CONFIG_N_GSM is not set


While i work on it every help is appreciated.

Many thanks
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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