problem with gen_update_var

problem with gen_update_var

[Antonino Daplas]

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Hi,

gen_update_var will break panning/wrapping since it passes info->var to
fb_pan_display.  However, fbcon updates display->var.

Tony

 





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--- fbgen.c.orig	Mon Jun 10 06:30:29 2002
+++ fbgen.c	Mon Jun 10 06:26:44 2002
@@ -514,6 +514,9 @@
     
 	if (con == info->currcon) {
 		if (info->fbops->fb_pan_display) {
+			info->var.xoffset = fb_display[con].var.xoffset;
+			info->var.yoffset = fb_display[con].var.yoffset;
+			info->var.vmode = fb_display[con].var.vmode;
 			if ((err = info->fbops->fb_pan_display(&info->var, con, info)))
 				return err;
 		}

Re: problem with gen_update_var

[James Simmons]

> Hi,
>
> gen_update_var will break panning/wrapping since it passes info->var to
> fb_pan_display.  However, fbcon updates display->var.

It works. The var info struct fb_info is always the foreground console.
Notice gen_update_var is only called when it is the foreground console.


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Re: problem with gen_update_var

[Antonino Daplas]

On Tue, 2002-06-18 at 03:27, James Simmons wrote:
> 
> > Hi,
> >
> > gen_update_var will break panning/wrapping since it passes info->var to
> > fb_pan_display.  However, fbcon updates display->var.
> 
> It works. The var info struct fb_info is always the foreground console.
> Notice gen_update_var is only called when it is the foreground console.
> 
> 
In ywrap_up in fbcon.c, it has this code:

    p->var.xoffset = 0;
    p->var.yoffset = p->yscroll*fontheight(p);
    p->var.vmode |= FB_VMODE_YWRAP;
    p->fb_info->updatevar(unit, p->fb_info);

(*p is struct display).  gen_update_var will call pan_display(info->var,
con, info).  But as can be seen, info->var is not updated by ywrap_up.  

Unless, the low-level driver's implementation is to get the offsets 
from fb_display[con].var, that's the only time it will work.  But it
will break userland apps that will call pan_display(var, con, info)
expecting that the offsets contained in the passed var parameter will be
updated.

Tony


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Re: problem with gen_update_var

[James Simmons]

> In ywrap_up in fbcon.c, it has this code:
>
>     p->var.xoffset = 0;
>     p->var.yoffset = p->yscroll*fontheight(p);
>     p->var.vmode |= FB_VMODE_YWRAP;
>     p->fb_info->updatevar(unit, p->fb_info);
>
> (*p is struct display).  gen_update_var will call pan_display(info->var,
> con, info).

Only if con == currcon.

> But as can be seen, info->var is not updated by ywrap_up.

Your right. I will fix that.

> Unless, the low-level driver's implementation is to get the offsets
> from fb_display[con].var, that's the only time it will work.  But it
> will break userland apps that will call pan_display(var, con, info)
> expecting that the offsets contained in the passed var parameter will be
> updated.

Don't worry about userland apps. They can't pan non foreground consoles.
Only fbcon inside the kernel can.


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