Hi Helge,

On Tue, Jul 11, 2023 at 5:26 PM Helge Deller [off-list ref] wrote:

On 7/11/23 16:47, Sam Ravnborg wrote:

quoted

On Tue, Jul 11, 2023 at 08:24:40AM +0200, Thomas Zimmermann wrote:

quoted

Am 10.07.23 um 19:19 schrieb Sam Ravnborg:

quoted

On Mon, Jul 10, 2023 at 02:50:04PM +0200, Thomas Zimmermann wrote:

quoted

Remove the unused flags FBINFO_DEFAULT and FBINFO_FLAG_DEFAULT from
fbdev and drivers, as briefly discussed at [1]. Both flags were maybe
useful when fbdev had special handling for driver modules. With
commit 376b3ff54c9a ("fbdev: Nuke FBINFO_MODULE"), they are both 0
and have no further effect.

Patches 1 to 7 remove FBINFO_DEFAULT from drivers. Patches 2 to 5
split this by the way the fb_info struct is being allocated. All flags
are cleared to zero during the allocation.

Patches 8 to 16 do the same for FBINFO_FLAG_DEFAULT. Patch 8 fixes
an actual bug in how arch/sh uses the tokne for struct fb_videomode,
which is unrelated.

Patch 17 removes both flag constants from <linux/fb.h>

We have a few more flags that are unused - should they be nuked too?
FBINFO_HWACCEL_FILLRECT
FBINFO_HWACCEL_ROTATE
FBINFO_HWACCEL_XPAN

It seems those are there for completeness. Nothing sets _ROTATE,

I think some fbdev drivers had hardware acceleration for ROTATE in the
past. HWACCEL_XPAN is still in some drivers.

quoted

quoted

the others are simply never checked. According to the comments,
some are required, some are optional. I don't know what that
means.

I think it's OK if you remove those flags which aren't used anywhere,
e.g. FBINFO_HWACCEL_ROTATE.

Indeed.

quoted

quoted

IIRC there were complains about performance when Daniel tried to remove
fbcon acceleration, so not all _HWACCEL_ flags are unneeded.

Correct. I think COPYAREA and FILLRECT are the bare minimum to accelerate
fbcon, IMAGEBLIT is for showing the tux penguin (?),
XPAN/YPAN and YWRAP for some hardware screen panning needed by some drivers
(not sure if this is still used as I don't have such hardware, Geert?).

Yes, they are used.  Anything that is handled in drivers/video/fbdev/core/
is used:

$ git grep  HWACCEL_ -- drivers/video/fbdev/core/
drivers/video/fbdev/core/fbcon.c:       if ((info->flags &
FBINFO_HWACCEL_COPYAREA) &&
drivers/video/fbdev/core/fbcon.c:           !(info->flags &
FBINFO_HWACCEL_DISABLED))
drivers/video/fbdev/core/fbcon.c:       int good_pan = (cap &
FBINFO_HWACCEL_YPAN) &&
drivers/video/fbdev/core/fbcon.c:       int good_wrap = (cap &
FBINFO_HWACCEL_YWRAP) &&
drivers/video/fbdev/core/fbcon.c:       int fast_copyarea = (cap &
FBINFO_HWACCEL_COPYAREA) &&
drivers/video/fbdev/core/fbcon.c:               !(cap &
FBINFO_HWACCEL_DISABLED);
drivers/video/fbdev/core/fbcon.c:       int fast_imageblit = (cap &
FBINFO_HWACCEL_IMAGEBLIT) &&
drivers/video/fbdev/core/fbcon.c:               !(cap &
FBINFO_HWACCEL_DISABLED);

BTW, I'm surprised FBINFO_HWACCEL_FILLRECT is not handled.
But looking at the full history, it never was...

quoted

quoted

Leaving them in for reference/completeness might be an option; or not. I
have no strong feelings about those flags.

I'd say drop FBINFO_HWACCEL_ROTATE at least ?

Agreed.

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