Re: [PATCH] firmware/sysfb: Fix wrong stride when bits-per-pixel is calculated

[Thomas Zimmermann]

Hi,

thanks a lot to both of you for this bug fix.

Am 13.04.23 um 03:34 schrieb Pierre Asselin:
> > (not tested)
>
> Tested.  It fixes the regression on my laptop.
>
> > diff --git a/drivers/firmware/sysfb_simplefb.c
> > b/drivers/firmware/sysfb_simplefb.c
> > index 82c64cb9f531..9f5299d54732 100644
> > --- a/drivers/firmware/sysfb_simplefb.c
> > +++ b/drivers/firmware/sysfb_simplefb.c
> > @@ -56,10 +56,11 @@ __init bool sysfb_parse_mode(const struct screen_info
> > *si,
> >   	 * don't specify alpha channels.
> >   	 */
> >   	if (si->lfb_depth > 8) {
> > -		bits_per_pixel = max(max3(si->red_size + si->red_pos,
> > +		bits_per_pixel = max3(max3(si->red_size + si->red_pos,
> >   					  si->green_size + si->green_pos,
> >   					  si->blue_size + si->blue_pos),
> > -				     si->rsvd_size + si->rsvd_pos);
> > +				     si->rsvd_size + si->rsvd_pos,
> > +				     si->lfb_depth);

I'm OK with this change. There's a comment

 "The best solution is to compute bits_per_pixel here and ignore 
lfb_depth."

I'd change this to

 "The best solution is to compute bits_per_pixel here from the color 
bits, the reserved bits and the reported color depth; whatever is highest."

That will hopefully clarify the meaning of these max3() statements. They 
are not obvious at first.

Best regards
Thomas


> >   	} else {
> >   		bits_per_pixel = si->lfb_depth;
> >   	}

--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev

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