On Sat, Jun 23, 2007 at 11:04:24AM -0700, Andrew Morton wrote:
> On Sat, 23 Jun 2007 12:50:46 +0200 Michal Januszewski <[EMAIL PROTECTED]> 
> wrote:
> 
> > +   if (!refresh_specified)
> > +           refresh = 200;
> >     diff = refresh;
> >     best = -1;
> >     for (i = 0; i < dbsize; i++) {
> >             if (name_matches(db[i], name, namelen) ||
> >                 (res_specified && res_matches(db[i], xres, yres))) {
> >                     if(!fb_try_mode(var, info, &db[i], bpp)) {
> > -                           if(!refresh_specified || db[i].refresh == 
> > refresh)
> > +                           if (refresh_specified && db[i].refresh == 
> > refresh)
> >                                     return 1;
> >                             else {
> > -                                   if(diff > abs(db[i].refresh - refresh)) 
> > {
> > +                                   if (diff > abs(db[i].refresh - 
> > refresh)) {
> >                                             diff = abs(db[i].refresh - 
> > refresh);
> >                                             best = i;
> >                                     }
> > @@ -938,6 +940,7 @@ void fb_destroy_modelist(struct list_head *head)
> >             kfree(pos);
> >     }
> >  }
> > +EXPORT_SYMBOL_GPL(fb_destroy_modelist);
> >  
> 
> fbdev ignoramus asks: isn't this pretty risky?  People who were previously
> relying upon (or at least using) the kernel's default resolution will find
> their displays coming up in a quite different resolution.

The resolution will be unchanged (this part of the code is only executed
if either the name of the mode or the resolution are a match).

What can change is the refresh rate -- it can be set higher than what it
used to be before.  But since we're checking all modes with fb_try_mode(),
(which calls fb_check_var()), I think that this change should be safe.
 
To avoid any side effects we could also do the following:

        for (i = 0; i < dbsize; i++) {
                if (name_matches(db[i], name, namelen) ||
                    (res_specified && res_matches(db[i], xres, yres))) {
                        if(!fb_try_mode(var, info, &db[i], bpp)) {
                                if (refresh_specified && db[i].refresh == 
refresh)
                                        return 1;
                                else {
                                        if (diff > abs(db[i].refresh - 
refresh)) {
                                                diff = abs(db[i].refresh - 
refresh);
                                                best = i;
                                        }
                                }
                        }
                }
        }

        if (best != -1) {
                fb_try_mode(var, info, &db[best], bpp);
-               return 2;
+               return (refresh_specified) ? 2 : 1;
        }

which would ensure that 1 is returned if the refresh rate is not
explicitly specified, just as it is done currently:

                                if(!refresh_specified || db[i].refresh == 
refresh)
                                        return 1

I might be missing something here, so it would be nice if someone
involved in the fb development could comment on the proposed change.

> This change seems to be quite unrelated to the uvesafb stuff and should be
> in a separate patch from the export, which _is_ uvesafb-related.  I think. 
> If that's wrong then the changelog could do with some attention.

You're right, I'll split this into two patches in the next round.

Best regards,
Michal

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