[PATCH v4 1/2] fbcon: Silence fbcon logo on 'quiet' boots

[Petr Mladek]

On Fri 2019-01-11 15:04:32, Sergey Senozhatsky wrote:
> On (01/10/19 14:03), Prarit Bhargava wrote:
> > +++ b/drivers/video/fbdev/core/fbcon.c
> > @@ -649,11 +649,14 @@ static void fbcon_prepare_logo(struct vc_data *vc, struct fb_info *info,
> >  		kfree(save);
> >  	}
> >  
> > +	if (logo_shown == FBCON_LOGO_DONTSHOW)
> > +		return;
> 
> +	if (console_loglevel <= CONSOLE_LOGLEVEL_QUIET)
> +		return;
> 
> Would this two-liner do the trick?

But then the other functions, like fbcon_scroll() or fbcon_switch(),
would think that the logo was shown because logo_shown !=
FBCON_LOGO_DONTSHOW.

It might be possible to do logo_shown = FBCON_LOGO_DONTSHOW.
But I am not sure if it is safe, see below.

> 	-ss
> 
> > +
> >  	if (logo_lines > vc->vc_bottom) {
> >  		logo_shown = FBCON_LOGO_CANSHOW;
> >  		printk(KERN_INFO
> >  		       "fbcon_init: disable boot-logo (boot-logo bigger than screen).\n");
> > -	} else if (logo_shown != FBCON_LOGO_DONTSHOW) {
> > +	} else {
> >  		logo_shown = FBCON_LOGO_DRAW;
> >  		vc->vc_top = logo_lines;
> >  	}
> > @@ -1059,9 +1062,11 @@ static void fbcon_init(struct vc_data *vc, int init)
> >  
> >  	cap = info->flags;
> >  
> > -	if (vc != svc || logo_shown == FBCON_LOGO_DONTSHOW ||
> > -	    (info->fix.type == FB_TYPE_TEXT))
> > +	if (vc != svc || console_loglevel <= CONSOLE_LOGLEVEL_QUIET ||
> > +	    (info->fix.type == FB_TYPE_TEXT)) {
> >  		logo = 0;
> > +		logo_shown = FBCON_LOGO_DONTSHOW;

This has still the problem mentioned in the v3 feedback. It modifies
the global variable logo_shown even when vc != svc. You still need
check and explain why it is safe. It is not clear to me.

Best Regards,
Petr

> > +	}
> >  
> >  	if (var_to_display(p, &info->var, info))
> >  		return;
> > -- 
> > 2.17.2
> >