[PATCH 03/21] fbcon: Restore fbcon scrolling acceleration

Daniel Vetter
2022-01-31T21:06:51Z

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(-)

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)
--
2.33.0