github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-05-12 16:18:45 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity

lib/fonts: Fix bit position when rotating by 180 degrees

Browse Source 
Fix the horizontal bit position when rotating a glyph by 180°. The
original code in rotate_ud() rounded the value in width up to a
multiple of 8, aka the bit pitch, and calculated the rotated pixel
from that value. The new code stores the glyph's pitch in bit_pitch,
but fails to update the rotated pixel's output accordingly. Simply
replacing the variable does this.

The bug can be reproduced by setting a font with an unaligned width,
such as sun12x22, like this:

 setfont sun12x22
 echo 2 > /sys/class/graphics/fbcon/rotate

Without the fix, the font looks distorted.

Fixes: a30e9e6b01 ("lib/fonts: Refactor glyph-rotation helpers")
Closes: https://lore.gitlab.freedesktop.org/drm-ai-reviews/review-patch7-20260407092555.58816-8-tzimmermann@suse.de/
Cc: dri-devel@lists.freedesktop.org
Cc: linux-fbdev@vger.kernel.org
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Helge Deller <deller@gmx.de>
This commit is contained in:
Thomas Zimmermann 2026-04-28 10:28:43 +02:00 committed by Helge Deller
parent 0b996ae54d
commit d237f719b2
1 changed files with 1 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
lib/fonts/font_rotate.c
View File

@ -106,7 +106,7 @@ static void __font_glyph_rotate_180(const unsigned char *glyph,
for (y = 0; y < height; y++) {
for (x = 0; x < width; x++) {
if (font_glyph_test_bit(glyph, x, y, bit_pitch)) {
font_glyph_set_bit(out, width - (1 + x + shift), height - (1 + y),
font_glyph_set_bit(out, bit_pitch - 1 - x - shift, height - 1 - y,
bit_pitch);
}
}