Re: doubts

[Lucas Correia Villa Real <lucasvr@gobolinux.org>]

On Wednesday 26 May 2004 08:40, Manish RATHI wrote:
> Hi,
> In franebuffer  fb_info structure, there are 4 functions to be used by
> fbcon.c these are:

4? You asked for 3 functions :-)


> (*updatevar)();

This is a function called by fbcon.c when going to update a user defined part 
of the display, in order to pan/wrap; updatevar() usually sets the new 
driver's "var" xoffset and yoffset and then tells the video controller the 
new screen start address. 


> (*changevar)();

Oh, I didn't see any driver using that. In the case of fbcon_changevar, it 
just calls fbcon_setup (specifying not to show the logo again), which resets 
the framebuffer settings such as font and pan/wrap offsets. 

When one calls (*setvar)(), which modifies the display variable configuration, 
it checks for the existence of a non-null function pointer to changevar and 
if found, calls that function. I really don't know why a driver should need 
to restart things when changing var data. Could anyone help to clarify that?

> (*blank)();

This function does the screen blanking routine, not required to be implemented 
by the driver. There's a good explanation of it on skeletonfb.c.


> Could anybody tell me the logic of above functions. Although they are
> mentioned in pl110.c and vfb.c but only function header is given.
>
>
> Regards
> Manish

Cheers,
Lucas


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