linux-kernel - Re: [PATCH 03/21] fbcon: Restore fbcon scrolling acceleration

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Date:   Tue, 1 Feb 2022 11:17:44 +0100
From:   Helge Deller <deller@....de>
To:     Daniel Vetter <daniel.vetter@...ll.ch>,
        DRI Development <dri-devel@...ts.freedesktop.org>
Cc:     Intel Graphics Development <intel-gfx@...ts.freedesktop.org>,
        linux-fbdev@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        stable@...r.kernel.org, Claudio Suarez <cssk@...-c.es>,
        Dave Airlie <airlied@...il.com>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Pavel Machek <pavel@....cz>, Sam Ravnborg <sam@...nborg.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Javier Martinez Canillas <javierm@...hat.com>,
        Tomi Valkeinen <tomi.valkeinen@...com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Sven Schnelle <svens@...ckframe.org>,
        Gerd Hoffmann <kraxel@...hat.com>
Subject: Re: [PATCH 03/21] fbcon: Restore fbcon scrolling acceleration

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
>