* scrollmode selection problem
@ 2005-12-12 17:38 Knut Petersen
2005-12-13 0:36 ` Antonino A. Daplas
2005-12-13 11:07 ` Geert Uytterhoeven
0 siblings, 2 replies; 7+ messages in thread
From: Knut Petersen @ 2005-12-12 17:38 UTC (permalink / raw)
To: linux-fbdev-devel
Have a look at the following problem:
framebuffer memory size is 8MB
xres is 800, yres is 600, bpp is 8.
xres_virtual is 1024, yres_virtual is 8192.
font dimensions 8x16
check_var() and set_par() are called, set_par() decides that ywrap
scrolling is possible and sets FBINFO_HWACCEL_YWRAP.
Well, that decision is _wrong_ as 600/16 results in a 37 line display
height, 8 pixel lines at the bottom are unused. But they are displayed,
and obviously they contain garbage as YWRAP scrolling is selected by
updatescrollmode().
As the driver does know nothing about fonts, the obvious place to
change is updatescrollmode().
int good_wrap = (cap & FBINFO_HWACCEL_YWRAP) &&
divides(ywrap, vc->vc_font.height) &&
divides(vc->vc_font.height, vyres) &&
divides(vc->vc_font.height, yres);
would be a solution, but I don´t like it. There is no real reason that
ywrap
scrolling should be disallowed when divides(vc->vc_font.height, vyres)
or divides(vc->vc_font.height, yres) are false ... only limitations of the
fbcon scrolling code.
Has someone already written code to remove that limitation?
cu,
Knut
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^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: scrollmode selection problem
2005-12-12 17:38 scrollmode selection problem Knut Petersen
@ 2005-12-13 0:36 ` Antonino A. Daplas
2005-12-13 11:07 ` Geert Uytterhoeven
1 sibling, 0 replies; 7+ messages in thread
From: Antonino A. Daplas @ 2005-12-13 0:36 UTC (permalink / raw)
To: linux-fbdev-devel; +Cc: Knut Petersen
Knut Petersen wrote:
> Have a look at the following problem:
>
> framebuffer memory size is 8MB
> xres is 800, yres is 600, bpp is 8.
> xres_virtual is 1024, yres_virtual is 8192.
> font dimensions 8x16
>
> check_var() and set_par() are called, set_par() decides that ywrap
> scrolling is possible and sets FBINFO_HWACCEL_YWRAP.
>
> Well, that decision is _wrong_ as 600/16 results in a 37 line display
> height, 8 pixel lines at the bottom are unused. But they are displayed,
> and obviously they contain garbage as YWRAP scrolling is selected by
> updatescrollmode().
I agree.
>
> As the driver does know nothing about fonts, the obvious place to
> change is updatescrollmode().
>
> int good_wrap = (cap & FBINFO_HWACCEL_YWRAP) &&
> divides(ywrap, vc->vc_font.height) &&
> divides(vc->vc_font.height, vyres) &&
> divides(vc->vc_font.height, yres);
>
> would be a solution, but I don´t like it. There is no real reason that
It's a solution, and the correct one with the current code.
> ywrap
> scrolling should be disallowed when divides(vc->vc_font.height, vyres)
> or divides(vc->vc_font.height, yres) are false ... only limitations of the
> fbcon scrolling code.
>
> Has someone already written code to remove that limitation?
None that I know of. Unfortunately, there's only a sprinkling of hardware
that supports ywrap, so you're the best bet to do that (hint, hint :-)
Tony
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^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: scrollmode selection problem
2005-12-12 17:38 scrollmode selection problem Knut Petersen
2005-12-13 0:36 ` Antonino A. Daplas
@ 2005-12-13 11:07 ` Geert Uytterhoeven
2005-12-13 12:28 ` Knut Petersen
1 sibling, 1 reply; 7+ messages in thread
From: Geert Uytterhoeven @ 2005-12-13 11:07 UTC (permalink / raw)
To: Linux Frame Buffer Device Development
[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: TEXT/PLAIN; charset=UTF-8, Size: 1701 bytes --]
On Mon, 12 Dec 2005, Knut Petersen wrote:
> Have a look at the following problem:
>
> framebuffer memory size is 8MB
> xres is 800, yres is 600, bpp is 8.
> xres_virtual is 1024, yres_virtual is 8192.
> font dimensions 8x16
>
> check_var() and set_par() are called, set_par() decides that ywrap
> scrolling is possible and sets FBINFO_HWACCEL_YWRAP.
>
> Well, that decision is _wrong_ as 600/16 results in a 37 line display
> height, 8 pixel lines at the bottom are unused. But they are displayed,
> and obviously they contain garbage as YWRAP scrolling is selected by
> updatescrollmode().
>
> As the driver does know nothing about fonts, the obvious place to
> change is updatescrollmode().
>
> int good_wrap = (cap & FBINFO_HWACCEL_YWRAP) &&
> divides(ywrap, vc->vc_font.height) &&
> divides(vc->vc_font.height, vyres) &&
> divides(vc->vc_font.height, yres);
>
> would be a solution, but I don´t like it. There is no real reason that ywrap
> scrolling should be disallowed when divides(vc->vc_font.height, vyres)
> or divides(vc->vc_font.height, yres) are false ... only limitations of the
> fbcon scrolling code.
>
> Has someone already written code to remove that limitation?
This used to work fine (garbage in borders was cleared when fbcon did
pan/wrap), so I consider it a regression.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: scrollmode selection problem
2005-12-13 11:07 ` Geert Uytterhoeven
@ 2005-12-13 12:28 ` Knut Petersen
2005-12-13 12:35 ` Geert Uytterhoeven
2005-12-13 16:04 ` Antonino A. Daplas
0 siblings, 2 replies; 7+ messages in thread
From: Knut Petersen @ 2005-12-13 12:28 UTC (permalink / raw)
To: linux-fbdev-devel
>This used to work fine (garbage in borders was cleared when fbcon did
>pan/wrap), so I consider it a regression.
>
>
>
Well, it definitely is broken. If you don´t have a quick fix, we should
disable
that code path for 2.6.15 as I suggested.
Our goal should be
int good_wrap = (cap & FBINFO_HWACCEL_YWRAP) &&
divides(ywrap, vc->vc_font.height) &&
- divides(vc->vc_font.height, vyres) &&
- divides(vc->vc_font.height, yres);
for one of the next releases.
cu,
Knut
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^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: scrollmode selection problem
2005-12-13 12:28 ` Knut Petersen
@ 2005-12-13 12:35 ` Geert Uytterhoeven
2005-12-13 16:04 ` Antonino A. Daplas
1 sibling, 0 replies; 7+ messages in thread
From: Geert Uytterhoeven @ 2005-12-13 12:35 UTC (permalink / raw)
To: Linux Frame Buffer Device Development
[-- Attachment #1: Type: TEXT/PLAIN, Size: 1028 bytes --]
On Tue, 13 Dec 2005, Knut Petersen wrote:
> > This used to work fine (garbage in borders was cleared when fbcon did
> > pan/wrap), so I consider it a regression.
> >
> >
> Well, it definitely is broken. If you don´t have a quick fix, we should
> disable
> that code path for 2.6.15 as I suggested.
>
> Our goal should be
>
> int good_wrap = (cap & FBINFO_HWACCEL_YWRAP) &&
> divides(ywrap, vc->vc_font.height) &&
> - divides(vc->vc_font.height, vyres) &&
> - divides(vc->vc_font.height, yres);
>
>
> for one of the next releases.
You're right, I was confused with ypan. Upon more reflections, for ywrap, it
probably never worked before.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: scrollmode selection problem
2005-12-13 12:28 ` Knut Petersen
2005-12-13 12:35 ` Geert Uytterhoeven
@ 2005-12-13 16:04 ` Antonino A. Daplas
2005-12-13 16:09 ` Antonino A. Daplas
1 sibling, 1 reply; 7+ messages in thread
From: Antonino A. Daplas @ 2005-12-13 16:04 UTC (permalink / raw)
To: linux-fbdev-devel
Knut Petersen wrote:
>
>> This used to work fine (garbage in borders was cleared when fbcon did
>> pan/wrap), so I consider it a regression.
>>
>>
>>
> Well, it definitely is broken. If you don´t have a quick fix, we should
> disable
> that code path for 2.6.15 as I suggested.
What if you insert
fbcon_clear_margins(vc, 1);
after
ops->update_start(info);
in ywrap_up() and ywrap_down() inf fbcon.c?
Tony
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^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: scrollmode selection problem
2005-12-13 16:04 ` Antonino A. Daplas
@ 2005-12-13 16:09 ` Antonino A. Daplas
0 siblings, 0 replies; 7+ messages in thread
From: Antonino A. Daplas @ 2005-12-13 16:09 UTC (permalink / raw)
To: Antonino A. Daplas; +Cc: linux-fbdev-devel
Antonino A. Daplas wrote:
> Knut Petersen wrote:
>>> This used to work fine (garbage in borders was cleared when fbcon did
>>> pan/wrap), so I consider it a regression.
>>>
>>>
>>>
>> Well, it definitely is broken. If you don´t have a quick fix, we should
>> disable
>> that code path for 2.6.15 as I suggested.
>
> What if you insert
>
> fbcon_clear_margins(vc, 1);
>
> after
> ops->update_start(info);
>
> in ywrap_up() and ywrap_down() inf fbcon.c?
Forget this, it won't work. ops->clear_margins will need to be
rewritten so it recognizes when it's in the ywrap boundary.
Tony
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^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2005-12-13 16:09 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2005-12-12 17:38 scrollmode selection problem Knut Petersen
2005-12-13 0:36 ` Antonino A. Daplas
2005-12-13 11:07 ` Geert Uytterhoeven
2005-12-13 12:28 ` Knut Petersen
2005-12-13 12:35 ` Geert Uytterhoeven
2005-12-13 16:04 ` Antonino A. Daplas
2005-12-13 16:09 ` Antonino A. Daplas
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