Re: Question about cfb_copyarea

On Sat, 2007-02-10 at 15:32 +0100, Juergen Beisert wrote: 
> Hi Petr,
> 
> On Wednesday 31 January 2007 10:12, Petr Vandrovec wrote:
> > Take a look at updatescrollmode() in fbcon.c - you must persuade this
> > function to use SCROLL_*_MOVE, not SCROLL_*_REDRAW.  FBINFO_READS_FAST
> > should be sufficient - or you can report fast bitblt + fast panning, or
> > fast bitblt + slow imageblit.  If you report no panning + fast bitblt +
> > fast imageblit, redraw is used :-(
> 
> I tried around to get fbcon to use SCROLL_MOVE. These are my current settings:
> 
> info->flags	= FBINFO_DEFAULT |
> 		  FBINFO_HWACCEL_COPYAREA |
> 		  FBINFO_HWACCEL_FILLRECT |
> 		  FBINFO_HWACCEL_IMAGEBLIT |
> 		  FBINFO_READS_FAST;
> With this settings updatescrollmode() decides to use SCROLL_MOVE.
> 
> Two things are coming up with this scroll mode (all in fbcon_scroll() ):
> 
>  1) why is the variable "logo_shown" always set to 0 for console 0? When in
>     console 0 it always ends up in "goto redraw_up;" But I have no logo on my
>     console? For other consoles than 0 "logo_shown" is -1
>     (=FBCON_LOGO_CANSHOW)
>  2) with the settings above active on another console then 0, the whole system
>     freezes immediately in ops->bmove() or ops->clear()????
>  2a) when I comment out the "logo_shown" check in fbcon_scroll() it also
>      freezes the whole system in console 0.
> 
> Any ideas?
> 

The global 'logo_shown' is only used at the very start, to display the
boot logo if it is equal to LOGO_DRAW. It basically forces the scroll
mode to redraw and gives space in the upper part of your screen. After
that 'logo_shown' is assigned the index of the foreground console
(usually 0) and your scroll settings are now used.

Basically, don't touch the 'logo_shown' variable.  If you don't want the
tux logo, then disable it in your kernel config.

As to why your driver freezes, I don't know.  Check if it also crashes
with cfbcopyarea first.

Tony



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