linux-kernel - Re: [PATCH v3 0/5] console: Miscellaneous clean-ups, do not use FNTCHARCNT() in fbcon.c

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Message-ID: <CAKMK7uF_AOrfTDVZwmxn_C-5sTBDu_v9KGH07wO5hTa98Z8Ucg@mail.gmail.com>
Date:   Thu, 19 Nov 2020 16:10:57 +0100
From:   Daniel Vetter <daniel@...ll.ch>
To:     Peilin Ye <yepeilin.cs@...il.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Linux Fbdev development list <linux-fbdev@...r.kernel.org>
Subject: Re: [PATCH v3 0/5] console: Miscellaneous clean-ups, do not use
 FNTCHARCNT() in fbcon.c

On Thu, Nov 19, 2020 at 9:33 AM Peilin Ye <yepeilin.cs@...il.com> wrote:
>
> On Sat, Nov 14, 2020 at 01:22:22PM +0100, Greg Kroah-Hartman wrote:
> > Ah, here's a hint:
> >       https://wiki.archlinux.org/index.php/Linux_console#Fonts
> >
> > The setfont tool should help you out here.
>
> setfont seems to work fine, I tried Georgian-Fixed16 (256 chars) and
> Uni2-VGA16 (512 chars) under /usr/share/consolefonts/ in my Ubuntu box,
> including setting all consoles to the same font:
>
> for i in {1..6}; do
>         sudo setfont -C /dev/tty${i} /usr/share/consolefonts/Georgian-Fixed16.psf.gz
> done
>
> Font rotation also seems to work fine:
>
> for i in {1..4}; do
>         echo $i | sudo tee /sys/class/graphics/fbcon/rotate
>         sleep 1
> done

Thanks a lot for checking all this.

> One last thing I can think of is tile blitting, but I don't have the
> hardware (e.g. a Matrox G400 card, see FB_TILEBLITTING in
> drivers/video/fbdev/Kconfig) at hand, nor did I figure out how to
> simulate it after searching for a while.  However based on the other
> tests above I believe vc->vc_font.charcount is set properly.

tbh I'll just go ahead and delete it if it's broken :-)

Userspace we have to keep working (and there's actually people
creating new products on top of drm display drivers using fbdev
emulation and /dev/fb/0 interface!), but kernel internal stuff like
fbcon acceleration we can trim pretty aggressively I think.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch