[U-Boot] Displaying characters on the display in u-boot

[Bhargav A K]

Hi All

Please bring up my post. I'm still waiting for an answer.

Kind regards
Bhargav
________________________________________
From: Bhargav A K
Sent: Friday, April 19, 2013 9:29 PM
To: u-boot at lists.denx.de; Anatolij Gustschin
Subject: RE: [U-Boot] Displaying characters on the display in u-boot

Hi All,

I have enabled the following configurations.
in my board's config header

#define CONFIG_VGA_AS_SINGLE_DEVICE
#define CONFIG_VIDEO
#define CONFIG_CFB_CONSOLE

video_hw_init() returns a pointer to GraphicsDevice structure.

It does the following
-----------------------------------------------------
omap4_GD.winSizeX = 480; //__raw_readl()
omap4_GD.winSizeY = 800;
omap4_GD.gdfBytesPP = 4;
omap4_GD.gdfIndex = GDF_32BIT_X888RGB;

__raw_writel(0xA5000000, DISPC_GFX_BA0);
omap4_GD.frameAdrs = __raw_readl(DISPC_GFX_BA0);

initDisplay(); // Do all other clocks, GPIOs, OMAP4 registers specific for LCD(DSI, DISPC, DSS).
------------------------------------------------------

board_video_init() is just a dummy call.

I did a console_assign() to redirect stderr and stdout to vga.
All the printf's doesn't come on the serial console or the LCD.

I tried using the video_drawstring(10, 20, "hello world"),
after resetting the stdout to serial. I see all the "printf's" on the
serial console, but the string from video_drawstring()(hello world)
won't come on the LCD even after syncing LCD pipelines (GO_LCD in OMAP4470).

Then I just exported the lcd_drawchars() function into my LCD code,
tried to write characters to the LCD, nothing came onto the screen.

Please point out where I am going wrong.

Kind regardsn
Bhargav
________________________________________
From: Bhargav A K
Sent: Wednesday, March 27, 2013 10:04 PM
To: Anatolij Gustschin
Cc: u-boot at lists.denx.de
Subject: RE: [U-Boot] Displaying characters on the display in u-boot

Anatolij,

Thank you very very much, I will implement this very soon.
If I face any issues, which I won't after such excellent tutoring from you,
can I revert back to you ?

Thanks again :)...

> Yes. If board specific video initialization is done elsewhere the
> board_video_init() can be a dummy function.

I shall make it a dummy, and I have to make sure it return success,
as I have done it elsewhere.

Kind regards
Bhargav
________________________________________
From: Anatolij Gustschin [agust at denx.de]
Sent: Wednesday, March 27, 2013 9:57 PM
To: Bhargav A K
Cc: u-boot at lists.denx.de
Subject: Re: [U-Boot] Displaying characters on the display in u-boot

Hi,

On Wed, 27 Mar 2013 21:05:55 +0530
Bhargav A K <bhargav.ak at sasken.com> wrote:
...
> > What U-Boot version do you use?
>
> U-Boot 1.1.4-geb3fa991 (Feb 21 2013 - 10:11:04)
> (output of version command)

Very old, ;-).

> > This video_set_lut() function is only needed if you use 8 bits per
> > pixel frame buffer.
>
> So can I comment it out, (or) just make a dummy call and dummy return from it.
> It wont affect my character(text) rendering on the display, correct ?

yes, just provide a dummy video_set_lut(). If you do not use the
GDF__8BIT_INDEX framebuffer format, the rendering will work.

> My last question, the board_video_init() function just initializes the board
> in display/video mode. For example if I have a GPIO to switch b/w command and
> video modes and a GPIO to switch on the LCD, etc., I'll have to do all such
> functions in it.
>
> But if all of those are already done, I can just return a dummy from the
> function ?

Yes. If board specific video initialisation is done elsewhere the
board_video_init() can be a dummy function. Some video drivers
expect board_video_init() to return frame buffer base address but
i.e. in omap3 driver it returns 0 for successful video init or an
error code in case the board specific video init fails, thus
preventing further initialisation in the cfb_console driver.

Thanks,

Anatolij

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