fbcon: smart blitter usage for scrolling

This patch replaces the current SCROLL_MOVE method with smarter method using
the same logic as the SCROLL_REDRAW method.  This brings these two methods
much closer in performance and benefits all framebuffers which uses the
SCROLL_MOVE method.

[adaplas]
- remove unnecessary char attribute checking
- whitespace cleanups and 80-column line fixes

Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: Antonino Daplas <adaplas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 68 insertions, 8 deletions

diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c
index 73813c60d03a..7888e319f9e1 100644
--- a/drivers/video/console/fbcon.c
+++ b/drivers/video/console/fbcon.c
@@ -1704,6 +1704,56 @@ static void fbcon_redraw_move(struct vc_data *vc, struct display *p,
         }
 }
 
+static void fbcon_redraw_blit(struct vc_data *vc, struct fb_info *info,
+                        struct display *p, int line, int count, int ycount)
+{
+        int offset = ycount * vc->vc_cols;
+        unsigned short *d = (unsigned short *)
+            (vc->vc_origin + vc->vc_size_row * line);
+        unsigned short *s = d + offset;
+        struct fbcon_ops *ops = info->fbcon_par;
+
+        while (count--) {
+                unsigned short *start = s;
+                unsigned short *le = advance_row(s, 1);
+                unsigned short c;
+                int x = 0;
+
+                do {
+                        c = scr_readw(s);
+
+                        if (c == scr_readw(d)) {
+                                if (s > start) {
+                                        ops->bmove(vc, info, line + ycount, x,
+                                                   line, x, 1, s-start);
+                                        x += s - start + 1;
+                                        start = s + 1;
+                                } else {
+                                        x++;
+                                        start++;
+                                }
+                        }
+
+                        scr_writew(c, d);
+                        console_conditional_schedule();
+                        s++;
+                        d++;
+                } while (s < le);
+                if (s > start)
+                        ops->bmove(vc, info, line + ycount, x, line, x, 1,
+                                   s-start);
+                console_conditional_schedule();
+                if (ycount > 0)
+                        line++;
+                else {
+                        line--;
+                        /* NOTE: We subtract two lines from these pointers */
+                        s -= vc->vc_size_row;
+                        d -= vc->vc_size_row;
+                }
+        }
+}
+
 static void fbcon_redraw(struct vc_data *vc, struct display *p,
                          int line, int count, int offset)
 {
@@ -1789,7 +1839,6 @@ static int fbcon_scroll(struct vc_data *vc, int t, int b, int dir,
 {
         struct fb_info *info = registered_fb[con2fb_map[vc->vc_num]];
         struct display *p = &fb_display[vc->vc_num];
-        struct fbcon_ops *ops = info->fbcon_par;
         int scroll_partial = info->flags & FBINFO_PARTIAL_PAN_OK;
 
         if (fbcon_is_inactive(vc, info))
@@ -1813,10 +1862,15 @@ static int fbcon_scroll(struct vc_data *vc, int t, int b, int dir,
                         goto redraw_up;
                 switch (p->scrollmode) {
                 case SCROLL_MOVE:
-                        ops->bmove(vc, info, t + count, 0, t, 0,
-                                    b - t - count, vc->vc_cols);
-                        ops->clear(vc, info, b - count, 0, count,
-                                  vc->vc_cols);
+                        fbcon_redraw_blit(vc, info, p, t, b - t - count,
+                                     count);
+                        fbcon_clear(vc, b - count, 0, count, vc->vc_cols);
+                        scr_memsetw((unsigned short *) (vc->vc_origin +
+                                                        vc->vc_size_row *
+                                                        (b - count)),
+                                    vc->vc_video_erase_char,
+                                    vc->vc_size_row * count);
+                        return 1;
                         break;
 
                 case SCROLL_WRAP_MOVE:
@@ -1899,9 +1953,15 @@ static int fbcon_scroll(struct vc_data *vc, int t, int b, int dir,
                         goto redraw_down;
                 switch (p->scrollmode) {
                 case SCROLL_MOVE:
-                        ops->bmove(vc, info, t, 0, t + count, 0,
-                                    b - t - count, vc->vc_cols);
-                        ops->clear(vc, info, t, 0, count, vc->vc_cols);
+                        fbcon_redraw_blit(vc, info, p, b - 1, b - t - count,
+                                     -count);
+                        fbcon_clear(vc, t, 0, count, vc->vc_cols);
+                        scr_memsetw((unsigned short *) (vc->vc_origin +
+                                                        vc->vc_size_row *
+                                                        t),
+                                    vc->vc_video_erase_char,
+                                    vc->vc_size_row * count);
+                        return 1;
                         break;
 
                 case SCROLL_WRAP_MOVE: