Re: [PATCH] Re: black screen in X, linux-2.4.0-test5

[Nathan Hand]

On Wed, Aug 09, 2000 at 10:50:10AM +0200, Petr Vandrovec wrote:
> 
> Hmm.I'm looking into vgacon and I just cannot get idea why ordering 
> of vgacon_switch and vga_set_palette can matter, as vgacon_switch is 
> simple memcpy() and vga_set_palette just programs palette... Looking 
> at code again...  Oops. Hey, James made a bug... Code in console.c 
> should read
> 
> if (redraw) {
>    int updateregion;
>    
>    set_origin(currcons);
>    updateregion = sw->con_switch(vc_cons[currcons].d);
>    set_palette(currcons);
>    if (updateregion && (vcmode != KD_GRAPHICS))
>       do_update_region(currcons, origin, screenbuf_size / 2);
> }
> 
> as con_switch does not return success/failure, but it returns whether
> screen was repainted by con_switch (0) or whether update_region should
> be invoked (1)... I believe that it will solve your problem.
> 
> If it solves your problem, tell me and I'll resend patch below
> to Linus.

It does. I wrote a similar patch earlier today which just forced
vgacon to always return 1, but this was a brute force hack. Your
patch is clearly more correct.

Linus has entered a different patch which works in char/vt.c and
puts explicit set_palette calls before each unblank_screen. I've
not yet tried his patch. Other people have said it does work.

I think yours makes more sense though because you say con_switch
doesn't return success/failure, but instead whether an update is
needed. So set_palette should never have been in the if-block.

I prefer your patch. Please resend to Linus so he can choose the
patch he prefers.

> --- linux/drivers/char/console.c	Wed Jul 19 00:57:28 2000
> +++ linux/drivers/char/console.c	Wed Aug  9 10:44:35 2000
> @@ -586,12 +586,14 @@
>  	}
>  
>  	if (redraw) {
> +		int updateregion;
> +		
>  		set_origin(currcons);
> -		if (sw->con_switch(vc_cons[currcons].d) && vcmode != KD_GRAPHICS) {
> -			/* Update the screen contents */
> -			set_palette(currcons);
> +		updateregion = sw->con_switch(vc_cons[currcons].d);
> +		set_palette(currcons);
> +		/* Update the screen contents */
> +		if (updateregion && (vcmode != KD_GRAPHICS))
>  			do_update_region(currcons, origin, screenbuf_size/2);
> -		}
>  	}
>  	set_cursor(currcons);
>  	if (is_switch) {