Re: [Linux-fbdev-devel] board with broken vga ...

[Sven L. <lu...@la...>]

On Thu, Jul 18, 2002 at 11:42:57AM +0200, Petr Vandrovec wrote:
> On 18 Jul 02 at 9:51, Sven Luther wrote:
> > 
> > Ok, that said, i suppose ours are the only boards with such problems,
> > but since there is so much taken out of the drivers in your new setup
> > and put in a common place, would it not solve this problem if there were
> > an additional function which driver could provide (or fill in NULL if
> > there was no proble), for retrieving this data, which fbcon can write
> > back later on ?
> 
> Unfortunately there is no such hook. Fortunately call sequence is:

Yes, i know, but would such a hook be a good addition for the new API or
something ? 

Altough, it is true that maybe only pm2fb and pm3fb will make use of it,
it would be cleaner than patching vgacon code for it.

> your drivers's init
>    --> look and init devices
>        --> call register_framebuffer
>            --> VGACON reads contents of VGA buffer

So vgacon is responsible for (wrongly) reading the text data from the
board.

>            --> call to fbdev setvar
>            --> upper layer restores screen
> ...
> With matroxfb I moved all initialization which changes framebuffer layout
> to the setvar call, and so VGACON finds hardware in VGA, and not MMIO,
> state.

Mmm, that may be an idea, provided the normal VGA stuff is not broken.

> You can look at drivers/char/console.c: take_over_console calls
> save_screen, which in turn calls con_save_screen method of vgacon.
> So you can try directly overwritting vgacon's savescreen procedure
> 
> extern struct consw vga_con;
> vga_con.con_save_screen = myOwnSaveScreen;
> 
> if you find that your fbdev is primary VGA device. Of course it is
> not tested, and I cannot recommend doing that...

Ok, i will look at it, thanks.

Friendly,

Sven Luther
>                                                     Petr
>