diff mbox series

[03/21] fbcon: Restore fbcon scrolling acceleration

Message ID 20220131210552.482606-4-daniel.vetter@ffwll.ch (mailing list archive)
State Superseded
Headers show
Series some fbcon patches, mostly locking | expand

Commit Message

Daniel Vetter Jan. 31, 2022, 9:05 p.m. UTC
This functionally undoes 39aead8373b3 ("fbcon: Disable accelerated
scrolling"), but behind the FRAMEBUFFER_CONSOLE_LEGACY_ACCELERATION
option.

References: https://lore.kernel.org/dri-devel/feea8303-2b83-fc36-972c-4fc8ad723bde@gmx.de/
Fixes: 39aead8373b3 ("fbcon: Disable accelerated scrolling")
Cc: Helge Deller <deller@gmx.de>
Cc: <stable@vger.kernel.org> # v5.11+
Cc: Claudio Suarez <cssk@net-c.es>
Cc: Dave Airlie <airlied@gmail.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Linux Fbdev development list <linux-fbdev@vger.kernel.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Javier Martinez Canillas <javierm@redhat.com>
Cc: DRI Development <dri-devel@lists.freedesktop.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Cc: Claudio Suarez <cssk@net-c.es>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Sven Schnelle <svens@stackframe.org>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
---
 drivers/video/fbdev/core/fbcon.c | 48 ++++++++++++++++++++++++++++----
 1 file changed, 42 insertions(+), 6 deletions(-)

Comments

Helge Deller Feb. 1, 2022, 10:16 a.m. UTC | #1
On 1/31/22 22:05, Daniel Vetter wrote:
> This functionally undoes 39aead8373b3 ("fbcon: Disable accelerated
> scrolling"), but behind the FRAMEBUFFER_CONSOLE_LEGACY_ACCELERATION
> option.

you have two trivial copy-n-paste errors in this patch which still prevent the
console acceleration.

> diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
> index 2ff90061c7f3..39dc18a5de86 100644
> --- a/drivers/video/fbdev/core/fbcon.c
> +++ b/drivers/video/fbdev/core/fbcon.c
> @@ -1125,13 +1125,15 @@ static void fbcon_init(struct vc_data *vc, int init)
>
>  	ops->graphics = 0;
>
> -	/*
> -	 * No more hw acceleration for fbcon.
> -	 *
> -	 * FIXME: Garbage collect all the now dead code after sufficient time
> -	 * has passed.
> -	 */
> +#ifdef CONFIG_FRAMEBUFFER_CONSOLE_ROTATION

should be:
#ifdef CONFIG_FRAMEBUFFER_CONSOLE_LEGACY_ACCELERATION


> +	if ((info->flags & FBINFO_HWACCEL_COPYAREA) &&
> +	    !(info->flags & FBINFO_HWACCEL_DISABLED))
> +		p->scrollmode = SCROLL_MOVE;
> +	else /* default to something safe */
> +		p->scrollmode = SCROLL_REDRAW;
> +#else
>  	p->scrollmode = SCROLL_REDRAW;
> +#endif
>
>  	/*
>  	 *  ++guenther: console.c:vc_allocate() relies on initializing
> @@ -1971,15 +1973,49 @@ static void updatescrollmode(struct fbcon_display *p,
>  {
>  	struct fbcon_ops *ops = info->fbcon_par;
>  	int fh = vc->vc_font.height;
> +	int cap = info->flags;
> +	u16 t = 0;
> +	int ypan = FBCON_SWAP(ops->rotate, info->fix.ypanstep,
> +			      info->fix.xpanstep);
> +	int ywrap = FBCON_SWAP(ops->rotate, info->fix.ywrapstep, t);
>  	int yres = FBCON_SWAP(ops->rotate, info->var.yres, info->var.xres);
>  	int vyres = FBCON_SWAP(ops->rotate, info->var.yres_virtual,
>  				   info->var.xres_virtual);
> +	int good_pan = (cap & FBINFO_HWACCEL_YPAN) &&
> +		divides(ypan, vc->vc_font.height) && vyres > yres;
> +	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);
> +	int reading_fast = cap & FBINFO_READS_FAST;
> +	int fast_copyarea = (cap & FBINFO_HWACCEL_COPYAREA) &&
> +		!(cap & FBINFO_HWACCEL_DISABLED);
> +	int fast_imageblit = (cap & FBINFO_HWACCEL_IMAGEBLIT) &&
> +		!(cap & FBINFO_HWACCEL_DISABLED);
>
>  	p->vrows = vyres/fh;
>  	if (yres > (fh * (vc->vc_rows + 1)))
>  		p->vrows -= (yres - (fh * vc->vc_rows)) / fh;
>  	if ((yres % fh) && (vyres % fh < yres % fh))
>  		p->vrows--;
> +
> +	if (good_wrap || good_pan) {
> +		if (reading_fast || fast_copyarea)
> +			p->scrollmode = good_wrap ?
> +				SCROLL_WRAP_MOVE : SCROLL_PAN_MOVE;
> +		else
> +			p->scrollmode = good_wrap ? SCROLL_REDRAW :
> +				SCROLL_PAN_REDRAW;
> +	} else {
> +		if (reading_fast || (fast_copyarea && !fast_imageblit))
> +			p->scrollmode = SCROLL_MOVE;
> +		else
> +			p->scrollmode = SCROLL_REDRAW;
> +	}
> +
> +#ifndef CONFIG_FRAMEBUFFER_CONSOLE_ROTATION

same here... it needs to be:
#ifdef CONFIG_FRAMEBUFFER_CONSOLE_LEGACY_ACCELERATION


> +	p->scrollmode = SCROLL_REDRAW;
> +#endif
>  }
>
>  #define PITCH(w) (((w) + 7) >> 3)
>

still reviewing the other patches...

Helge
Helge Deller Feb. 1, 2022, 10:17 a.m. UTC | #2
On 2/1/22 11:16, Helge Deller wrote:
> On 1/31/22 22:05, Daniel Vetter wrote:
>> This functionally undoes 39aead8373b3 ("fbcon: Disable accelerated
>> scrolling"), but behind the FRAMEBUFFER_CONSOLE_LEGACY_ACCELERATION
>> option.
>
> you have two trivial copy-n-paste errors in this patch which still prevent the
> console acceleration.
>
>> diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
>> index 2ff90061c7f3..39dc18a5de86 100644
>> --- a/drivers/video/fbdev/core/fbcon.c
>> +++ b/drivers/video/fbdev/core/fbcon.c
>> @@ -1125,13 +1125,15 @@ static void fbcon_init(struct vc_data *vc, int init)
>>
>>  	ops->graphics = 0;
>>
>> -	/*
>> -	 * No more hw acceleration for fbcon.
>> -	 *
>> -	 * FIXME: Garbage collect all the now dead code after sufficient time
>> -	 * has passed.
>> -	 */
>> +#ifdef CONFIG_FRAMEBUFFER_CONSOLE_ROTATION
>
> should be:
> #ifdef CONFIG_FRAMEBUFFER_CONSOLE_LEGACY_ACCELERATION
>
>
>> +	if ((info->flags & FBINFO_HWACCEL_COPYAREA) &&
>> +	    !(info->flags & FBINFO_HWACCEL_DISABLED))
>> +		p->scrollmode = SCROLL_MOVE;
>> +	else /* default to something safe */
>> +		p->scrollmode = SCROLL_REDRAW;
>> +#else
>>  	p->scrollmode = SCROLL_REDRAW;
>> +#endif
>>
>>  	/*
>>  	 *  ++guenther: console.c:vc_allocate() relies on initializing
>> @@ -1971,15 +1973,49 @@ static void updatescrollmode(struct fbcon_display *p,
>>  {
>>  	struct fbcon_ops *ops = info->fbcon_par;
>>  	int fh = vc->vc_font.height;
>> +	int cap = info->flags;
>> +	u16 t = 0;
>> +	int ypan = FBCON_SWAP(ops->rotate, info->fix.ypanstep,
>> +			      info->fix.xpanstep);
>> +	int ywrap = FBCON_SWAP(ops->rotate, info->fix.ywrapstep, t);
>>  	int yres = FBCON_SWAP(ops->rotate, info->var.yres, info->var.xres);
>>  	int vyres = FBCON_SWAP(ops->rotate, info->var.yres_virtual,
>>  				   info->var.xres_virtual);
>> +	int good_pan = (cap & FBINFO_HWACCEL_YPAN) &&
>> +		divides(ypan, vc->vc_font.height) && vyres > yres;
>> +	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);
>> +	int reading_fast = cap & FBINFO_READS_FAST;
>> +	int fast_copyarea = (cap & FBINFO_HWACCEL_COPYAREA) &&
>> +		!(cap & FBINFO_HWACCEL_DISABLED);
>> +	int fast_imageblit = (cap & FBINFO_HWACCEL_IMAGEBLIT) &&
>> +		!(cap & FBINFO_HWACCEL_DISABLED);
>>
>>  	p->vrows = vyres/fh;
>>  	if (yres > (fh * (vc->vc_rows + 1)))
>>  		p->vrows -= (yres - (fh * vc->vc_rows)) / fh;
>>  	if ((yres % fh) && (vyres % fh < yres % fh))
>>  		p->vrows--;
>> +
>> +	if (good_wrap || good_pan) {
>> +		if (reading_fast || fast_copyarea)
>> +			p->scrollmode = good_wrap ?
>> +				SCROLL_WRAP_MOVE : SCROLL_PAN_MOVE;
>> +		else
>> +			p->scrollmode = good_wrap ? SCROLL_REDRAW :
>> +				SCROLL_PAN_REDRAW;
>> +	} else {
>> +		if (reading_fast || (fast_copyarea && !fast_imageblit))
>> +			p->scrollmode = SCROLL_MOVE;
>> +		else
>> +			p->scrollmode = SCROLL_REDRAW;
>> +	}
>> +
>> +#ifndef CONFIG_FRAMEBUFFER_CONSOLE_ROTATION
>
> same here... it needs to be:
> #ifdef CONFIG_FRAMEBUFFER_CONSOLE_LEGACY_ACCELERATION

actually:
#ifndef CONFIG_FRAMEBUFFER_CONSOLE_LEGACY_ACCELERATION

>
>
>> +	p->scrollmode = SCROLL_REDRAW;
>> +#endif
>>  }
>>
>>  #define PITCH(w) (((w) + 7) >> 3)
>>
>
> still reviewing the other patches...
>
> Helge
>
Daniel Vetter Feb. 1, 2022, 10:36 a.m. UTC | #3
On Tue, Feb 1, 2022 at 11:16 AM Helge Deller <deller@gmx.de> wrote:
>
> On 1/31/22 22:05, Daniel Vetter wrote:
> > This functionally undoes 39aead8373b3 ("fbcon: Disable accelerated
> > scrolling"), but behind the FRAMEBUFFER_CONSOLE_LEGACY_ACCELERATION
> > option.
>
> you have two trivial copy-n-paste errors in this patch which still prevent the
> console acceleration.

Duh :-(

But before we dig into details I think the big picture would be
better. I honestly don't like the #ifdef pile here that much. I wonder
whether your approach, also with GETVX/YRES adjusted somehow, wouldn't
look cleaner? Like I said in the cover letter I got mostly distracted
with fbcon locking last week, not really with this one here at all, so
maybe going with your 4 (or 2 if we squash them like I did here)
patches is neater?

Cheers, Daniel

>
> > diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
> > index 2ff90061c7f3..39dc18a5de86 100644
> > --- a/drivers/video/fbdev/core/fbcon.c
> > +++ b/drivers/video/fbdev/core/fbcon.c
> > @@ -1125,13 +1125,15 @@ static void fbcon_init(struct vc_data *vc, int init)
> >
> >       ops->graphics = 0;
> >
> > -     /*
> > -      * No more hw acceleration for fbcon.
> > -      *
> > -      * FIXME: Garbage collect all the now dead code after sufficient time
> > -      * has passed.
> > -      */
> > +#ifdef CONFIG_FRAMEBUFFER_CONSOLE_ROTATION
>
> should be:
> #ifdef CONFIG_FRAMEBUFFER_CONSOLE_LEGACY_ACCELERATION
>
>
> > +     if ((info->flags & FBINFO_HWACCEL_COPYAREA) &&
> > +         !(info->flags & FBINFO_HWACCEL_DISABLED))
> > +             p->scrollmode = SCROLL_MOVE;
> > +     else /* default to something safe */
> > +             p->scrollmode = SCROLL_REDRAW;
> > +#else
> >       p->scrollmode = SCROLL_REDRAW;
> > +#endif
> >
> >       /*
> >        *  ++guenther: console.c:vc_allocate() relies on initializing
> > @@ -1971,15 +1973,49 @@ static void updatescrollmode(struct fbcon_display *p,
> >  {
> >       struct fbcon_ops *ops = info->fbcon_par;
> >       int fh = vc->vc_font.height;
> > +     int cap = info->flags;
> > +     u16 t = 0;
> > +     int ypan = FBCON_SWAP(ops->rotate, info->fix.ypanstep,
> > +                           info->fix.xpanstep);
> > +     int ywrap = FBCON_SWAP(ops->rotate, info->fix.ywrapstep, t);
> >       int yres = FBCON_SWAP(ops->rotate, info->var.yres, info->var.xres);
> >       int vyres = FBCON_SWAP(ops->rotate, info->var.yres_virtual,
> >                                  info->var.xres_virtual);
> > +     int good_pan = (cap & FBINFO_HWACCEL_YPAN) &&
> > +             divides(ypan, vc->vc_font.height) && vyres > yres;
> > +     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);
> > +     int reading_fast = cap & FBINFO_READS_FAST;
> > +     int fast_copyarea = (cap & FBINFO_HWACCEL_COPYAREA) &&
> > +             !(cap & FBINFO_HWACCEL_DISABLED);
> > +     int fast_imageblit = (cap & FBINFO_HWACCEL_IMAGEBLIT) &&
> > +             !(cap & FBINFO_HWACCEL_DISABLED);
> >
> >       p->vrows = vyres/fh;
> >       if (yres > (fh * (vc->vc_rows + 1)))
> >               p->vrows -= (yres - (fh * vc->vc_rows)) / fh;
> >       if ((yres % fh) && (vyres % fh < yres % fh))
> >               p->vrows--;
> > +
> > +     if (good_wrap || good_pan) {
> > +             if (reading_fast || fast_copyarea)
> > +                     p->scrollmode = good_wrap ?
> > +                             SCROLL_WRAP_MOVE : SCROLL_PAN_MOVE;
> > +             else
> > +                     p->scrollmode = good_wrap ? SCROLL_REDRAW :
> > +                             SCROLL_PAN_REDRAW;
> > +     } else {
> > +             if (reading_fast || (fast_copyarea && !fast_imageblit))
> > +                     p->scrollmode = SCROLL_MOVE;
> > +             else
> > +                     p->scrollmode = SCROLL_REDRAW;
> > +     }
> > +
> > +#ifndef CONFIG_FRAMEBUFFER_CONSOLE_ROTATION
>
> same here... it needs to be:
> #ifdef CONFIG_FRAMEBUFFER_CONSOLE_LEGACY_ACCELERATION
>
>
> > +     p->scrollmode = SCROLL_REDRAW;
> > +#endif
> >  }
> >
> >  #define PITCH(w) (((w) + 7) >> 3)
> >
>
> still reviewing the other patches...
>
> Helge
Helge Deller Feb. 1, 2022, 11:01 a.m. UTC | #4
On 2/1/22 11:36, Daniel Vetter wrote:
> On Tue, Feb 1, 2022 at 11:16 AM Helge Deller <deller@gmx.de> wrote:
>>
>> On 1/31/22 22:05, Daniel Vetter wrote:
>>> This functionally undoes 39aead8373b3 ("fbcon: Disable accelerated
>>> scrolling"), but behind the FRAMEBUFFER_CONSOLE_LEGACY_ACCELERATION
>>> option.
>>
>> you have two trivial copy-n-paste errors in this patch which still prevent the
>> console acceleration.
>
> Duh :-(
>
> But before we dig into details I think the big picture would be
> better. I honestly don't like the #ifdef pile here that much.

Me neither.
The ifdefs give a better separation, but prevents that the compiler
checks the various paths when building.

> I wonder whether your approach, also with GETVX/YRES adjusted
> somehow, wouldn't look cleaner?
I think so.
You wouldn't even need to touch GETVX/YRES because the compiler
will optimize/reduce it from

#define GETVYRES(s,i) ({                           \
        (s == SCROLL_REDRAW || s == SCROLL_MOVE) ? \
        (i)->var.yres : (i)->var.yres_virtual; })

to just become:

#define GETVYRES(s,i) ((i)->var.yres)

> Like I said in the cover letter I got mostly distracted with fbcon
> locking last week, not really with this one here at all, so maybe
> going with your 4 (or 2 if we squash them like I did here) patches is
> neater?

The benefit of my patch series was, that it could be easily backported first,
and then cleaned up afterwards. Even a small additional backport patch to disable
the fbcon acceleration for DRM in the old releases would be easy.
But I'm not insisting on backporting the patches, if we find good way forward.

So, either with the 4 (or 2) patches would be OK for me (or even your approach).

Helge
Daniel Vetter Feb. 1, 2022, 1:45 p.m. UTC | #5
On Tue, Feb 1, 2022 at 12:01 PM Helge Deller <deller@gmx.de> wrote:
> On 2/1/22 11:36, Daniel Vetter wrote:
> > On Tue, Feb 1, 2022 at 11:16 AM Helge Deller <deller@gmx.de> wrote:
> >>
> >> On 1/31/22 22:05, Daniel Vetter wrote:
> >>> This functionally undoes 39aead8373b3 ("fbcon: Disable accelerated
> >>> scrolling"), but behind the FRAMEBUFFER_CONSOLE_LEGACY_ACCELERATION
> >>> option.
> >>
> >> you have two trivial copy-n-paste errors in this patch which still prevent the
> >> console acceleration.
> >
> > Duh :-(
> >
> > But before we dig into details I think the big picture would be
> > better. I honestly don't like the #ifdef pile here that much.
>
> Me neither.
> The ifdefs give a better separation, but prevents that the compiler
> checks the various paths when building.
>
> > I wonder whether your approach, also with GETVX/YRES adjusted
> > somehow, wouldn't look cleaner?
> I think so.
> You wouldn't even need to touch GETVX/YRES because the compiler
> will optimize/reduce it from
>
> #define GETVYRES(s,i) ({                           \
>         (s == SCROLL_REDRAW || s == SCROLL_MOVE) ? \
>         (i)->var.yres : (i)->var.yres_virtual; })
>
> to just become:
>
> #define GETVYRES(s,i) ((i)->var.yres)

Yeah, but you need to roll out your helper to all the callsites. But
since you #ifdef out info->scrollmode we should catch them all I
guess.

> > Like I said in the cover letter I got mostly distracted with fbcon
> > locking last week, not really with this one here at all, so maybe
> > going with your 4 (or 2 if we squash them like I did here) patches is
> > neater?
>
> The benefit of my patch series was, that it could be easily backported first,
> and then cleaned up afterwards. Even a small additional backport patch to disable
> the fbcon acceleration for DRM in the old releases would be easy.
> But I'm not insisting on backporting the patches, if we find good way forward.
>
> So, either with the 4 (or 2) patches would be OK for me (or even your approach).

The idea behind the squash was that it's then impossible to backport
without the Kconfig, and so we'll only enable this code when people
intentionally want it. Maybe I'm too paranoid?

Anyway, you feel like finishing off your approach? Or should I send
out v2 of this with the issues fixed you spotted? Like I said either
is fine with me.
-Daniel
Helge Deller Feb. 1, 2022, 2:52 p.m. UTC | #6
On 2/1/22 14:45, Daniel Vetter wrote:
> On Tue, Feb 1, 2022 at 12:01 PM Helge Deller <deller@gmx.de> wrote:
>> On 2/1/22 11:36, Daniel Vetter wrote:
>>> On Tue, Feb 1, 2022 at 11:16 AM Helge Deller <deller@gmx.de> wrote:
>>>>
>>>> On 1/31/22 22:05, Daniel Vetter wrote:
>>>>> This functionally undoes 39aead8373b3 ("fbcon: Disable accelerated
>>>>> scrolling"), but behind the FRAMEBUFFER_CONSOLE_LEGACY_ACCELERATION
>>>>> option.
>>>>
>>>> you have two trivial copy-n-paste errors in this patch which still prevent the
>>>> console acceleration.
>>>
>>> Duh :-(
>>>
>>> But before we dig into details I think the big picture would be
>>> better. I honestly don't like the #ifdef pile here that much.
>>
>> Me neither.
>> The ifdefs give a better separation, but prevents that the compiler
>> checks the various paths when building.
>>
>>> I wonder whether your approach, also with GETVX/YRES adjusted
>>> somehow, wouldn't look cleaner?
>> I think so.
>> You wouldn't even need to touch GETVX/YRES because the compiler
>> will optimize/reduce it from
>>
>> #define GETVYRES(s,i) ({                           \
>>         (s == SCROLL_REDRAW || s == SCROLL_MOVE) ? \
>>         (i)->var.yres : (i)->var.yres_virtual; })
>>
>> to just become:
>>
>> #define GETVYRES(s,i) ((i)->var.yres)
>
> Yeah, but you need to roll out your helper to all the callsites. But
> since you #ifdef out info->scrollmode we should catch them all I
> guess.

Right. That was the only reason why I ifdef'ed it out.
Technically we don't need that ifdef.

>>> Like I said in the cover letter I got mostly distracted with fbcon
>>> locking last week, not really with this one here at all, so maybe
>>> going with your 4 (or 2 if we squash them like I did here) patches is
>>> neater?
>>
>> The benefit of my patch series was, that it could be easily backported first,
>> and then cleaned up afterwards. Even a small additional backport patch to disable
>> the fbcon acceleration for DRM in the old releases would be easy.
>> But I'm not insisting on backporting the patches, if we find good way forward.
>>
>> So, either with the 4 (or 2) patches would be OK for me (or even your approach).
>
> The idea behind the squash was that it's then impossible to backport
> without the Kconfig,

Yes, my proposal was to simply revert the 2 patches and immediatly send
the Kconfig patch to disable it again.

> and so we'll only enable this code when people
> intentionally want it. Maybe I'm too paranoid?

I think you are too paranoid :-)
If all patches incl. the Kconfig patch are backported then people shouldn't
do it wrong.

> Anyway, you feel like finishing off your approach? Or should I send
> out v2 of this with the issues fixed you spotted? Like I said either
> is fine with me.

Ok, then let me try to finish my approach until tomorrow, and then you
check if you can and want to add your locking and other patches on top of it.
In the end I leave the decision which approach to take to you.
Ok?

Helge
Daniel Vetter Feb. 1, 2022, 4:30 p.m. UTC | #7
On Tue, Feb 1, 2022 at 3:52 PM Helge Deller <deller@gmx.de> wrote:
>
> On 2/1/22 14:45, Daniel Vetter wrote:
> > On Tue, Feb 1, 2022 at 12:01 PM Helge Deller <deller@gmx.de> wrote:
> >> On 2/1/22 11:36, Daniel Vetter wrote:
> >>> On Tue, Feb 1, 2022 at 11:16 AM Helge Deller <deller@gmx.de> wrote:
> >>>>
> >>>> On 1/31/22 22:05, Daniel Vetter wrote:
> >>>>> This functionally undoes 39aead8373b3 ("fbcon: Disable accelerated
> >>>>> scrolling"), but behind the FRAMEBUFFER_CONSOLE_LEGACY_ACCELERATION
> >>>>> option.
> >>>>
> >>>> you have two trivial copy-n-paste errors in this patch which still prevent the
> >>>> console acceleration.
> >>>
> >>> Duh :-(
> >>>
> >>> But before we dig into details I think the big picture would be
> >>> better. I honestly don't like the #ifdef pile here that much.
> >>
> >> Me neither.
> >> The ifdefs give a better separation, but prevents that the compiler
> >> checks the various paths when building.
> >>
> >>> I wonder whether your approach, also with GETVX/YRES adjusted
> >>> somehow, wouldn't look cleaner?
> >> I think so.
> >> You wouldn't even need to touch GETVX/YRES because the compiler
> >> will optimize/reduce it from
> >>
> >> #define GETVYRES(s,i) ({                           \
> >>         (s == SCROLL_REDRAW || s == SCROLL_MOVE) ? \
> >>         (i)->var.yres : (i)->var.yres_virtual; })
> >>
> >> to just become:
> >>
> >> #define GETVYRES(s,i) ((i)->var.yres)
> >
> > Yeah, but you need to roll out your helper to all the callsites. But
> > since you #ifdef out info->scrollmode we should catch them all I
> > guess.
>
> Right. That was the only reason why I ifdef'ed it out.
> Technically we don't need that ifdef.
>
> >>> Like I said in the cover letter I got mostly distracted with fbcon
> >>> locking last week, not really with this one here at all, so maybe
> >>> going with your 4 (or 2 if we squash them like I did here) patches is
> >>> neater?
> >>
> >> The benefit of my patch series was, that it could be easily backported first,
> >> and then cleaned up afterwards. Even a small additional backport patch to disable
> >> the fbcon acceleration for DRM in the old releases would be easy.
> >> But I'm not insisting on backporting the patches, if we find good way forward.
> >>
> >> So, either with the 4 (or 2) patches would be OK for me (or even your approach).
> >
> > The idea behind the squash was that it's then impossible to backport
> > without the Kconfig,
>
> Yes, my proposal was to simply revert the 2 patches and immediatly send
> the Kconfig patch to disable it again.
>
> > and so we'll only enable this code when people
> > intentionally want it. Maybe I'm too paranoid?
>
> I think you are too paranoid :-)
> If all patches incl. the Kconfig patch are backported then people shouldn't
> do it wrong.
>
> > Anyway, you feel like finishing off your approach? Or should I send
> > out v2 of this with the issues fixed you spotted? Like I said either
> > is fine with me.
>
> Ok, then let me try to finish my approach until tomorrow, and then you
> check if you can and want to add your locking and other patches on top of it.
> In the end I leave the decision which approach to take to you.
> Ok?

Sounds good, and yeah rough idea is that the maintainers + revert +
Kconfig should go in for rc3 or rc4 if we hit another bump, and the
locking stuff then in for -next (since it needs a backmerge and is
defo tricky stuff).

Cheers, Daniel
diff mbox series

Patch

diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
index 2ff90061c7f3..39dc18a5de86 100644
--- a/drivers/video/fbdev/core/fbcon.c
+++ b/drivers/video/fbdev/core/fbcon.c
@@ -1125,13 +1125,15 @@  static void fbcon_init(struct vc_data *vc, int init)
 
 	ops->graphics = 0;
 
-	/*
-	 * No more hw acceleration for fbcon.
-	 *
-	 * FIXME: Garbage collect all the now dead code after sufficient time
-	 * has passed.
-	 */
+#ifdef CONFIG_FRAMEBUFFER_CONSOLE_ROTATION
+	if ((info->flags & FBINFO_HWACCEL_COPYAREA) &&
+	    !(info->flags & FBINFO_HWACCEL_DISABLED))
+		p->scrollmode = SCROLL_MOVE;
+	else /* default to something safe */
+		p->scrollmode = SCROLL_REDRAW;
+#else
 	p->scrollmode = SCROLL_REDRAW;
+#endif
 
 	/*
 	 *  ++guenther: console.c:vc_allocate() relies on initializing
@@ -1971,15 +1973,49 @@  static void updatescrollmode(struct fbcon_display *p,
 {
 	struct fbcon_ops *ops = info->fbcon_par;
 	int fh = vc->vc_font.height;
+	int cap = info->flags;
+	u16 t = 0;
+	int ypan = FBCON_SWAP(ops->rotate, info->fix.ypanstep,
+			      info->fix.xpanstep);
+	int ywrap = FBCON_SWAP(ops->rotate, info->fix.ywrapstep, t);
 	int yres = FBCON_SWAP(ops->rotate, info->var.yres, info->var.xres);
 	int vyres = FBCON_SWAP(ops->rotate, info->var.yres_virtual,
 				   info->var.xres_virtual);
+	int good_pan = (cap & FBINFO_HWACCEL_YPAN) &&
+		divides(ypan, vc->vc_font.height) && vyres > yres;
+	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);
+	int reading_fast = cap & FBINFO_READS_FAST;
+	int fast_copyarea = (cap & FBINFO_HWACCEL_COPYAREA) &&
+		!(cap & FBINFO_HWACCEL_DISABLED);
+	int fast_imageblit = (cap & FBINFO_HWACCEL_IMAGEBLIT) &&
+		!(cap & FBINFO_HWACCEL_DISABLED);
 
 	p->vrows = vyres/fh;
 	if (yres > (fh * (vc->vc_rows + 1)))
 		p->vrows -= (yres - (fh * vc->vc_rows)) / fh;
 	if ((yres % fh) && (vyres % fh < yres % fh))
 		p->vrows--;
+
+	if (good_wrap || good_pan) {
+		if (reading_fast || fast_copyarea)
+			p->scrollmode = good_wrap ?
+				SCROLL_WRAP_MOVE : SCROLL_PAN_MOVE;
+		else
+			p->scrollmode = good_wrap ? SCROLL_REDRAW :
+				SCROLL_PAN_REDRAW;
+	} else {
+		if (reading_fast || (fast_copyarea && !fast_imageblit))
+			p->scrollmode = SCROLL_MOVE;
+		else
+			p->scrollmode = SCROLL_REDRAW;
+	}
+
+#ifndef CONFIG_FRAMEBUFFER_CONSOLE_ROTATION
+	p->scrollmode = SCROLL_REDRAW;
+#endif
 }
 
 #define PITCH(w) (((w) + 7) >> 3)