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m68k: Fix lost column on framebuffer debug console

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Move the cursor position rightward after rendering the character,
not before. This avoids complications that arise when the recursive
console_putc call has to wrap the line and/or scroll the display.
This also fixes the linewrap bug that crops off the rightmost column.

When the cursor is at the bottom of the display, a linefeed will not
move the cursor position further downward. Instead, the display scrolls
upward. Avoid the repeated add/subtract sequence by way of a single
subtraction at the initialization of console_struct_num_rows.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Finn Thain <fthain@linux-m68k.org>
Tested-by: Stan Johnson <userm57@yahoo.com>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/9d4e8c68a456d5f2bc254ac6f87a472d066ebd5e.1743115195.git.fthain@linux-m68k.org
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
This commit is contained in:
Finn Thain 2025-03-28 09:39:55 +11:00 committed by Geert Uytterhoeven
parent 8135422ae0
commit 210a1ce8ed
1 changed files with 21 additions and 10 deletions
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31
arch/m68k/kernel/head.S
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@ -3400,6 +3400,7 @@ L(console_clear_loop):
movel %d4,%d1 /* screen height in pixels */
divul %a0@(FONT_DESC_HEIGHT),%d1 /* d1 = max num rows */
subql #1,%d1 /* row range is 0 to num - 1 */
movel %d0,%a2@(Lconsole_struct_num_columns)
movel %d1,%a2@(Lconsole_struct_num_rows)
@ -3546,15 +3547,14 @@ func_start console_putc,%a0/%a1/%d0-%d7
cmpib #10,%d7
jne L(console_not_lf)
movel %a0@(Lconsole_struct_cur_row),%d0
addil #1,%d0
movel %d0,%a0@(Lconsole_struct_cur_row)
movel %a0@(Lconsole_struct_num_rows),%d1
cmpl %d1,%d0
jcs 1f
subil #1,%d0
movel %d0,%a0@(Lconsole_struct_cur_row)
console_scroll
jra L(console_exit)
1:
addql #1,%d0
movel %d0,%a0@(Lconsole_struct_cur_row)
jra L(console_exit)
L(console_not_lf):
@ -3581,12 +3581,6 @@ L(console_not_cr):
*/
L(console_not_home):
movel %a0@(Lconsole_struct_cur_column),%d0
addql #1,%a0@(Lconsole_struct_cur_column)
movel %a0@(Lconsole_struct_num_columns),%d1
cmpl %d1,%d0
jcs 1f
console_putc #'\n' /* recursion is OK! */
1:
movel %a0@(Lconsole_struct_cur_row),%d1
/*
@ -3633,6 +3627,23 @@ L(console_do_font_scanline):
addq #1,%d1
dbra %d7,L(console_read_char_scanline)
/*
* Register usage in the code below:
* a0 = pointer to console globals
* d0 = cursor column
* d1 = cursor column limit
*/
lea %pc@(L(console_globals)),%a0
movel %a0@(Lconsole_struct_cur_column),%d0
addql #1,%d0
movel %d0,%a0@(Lconsole_struct_cur_column) /* Update cursor pos */
movel %a0@(Lconsole_struct_num_columns),%d1
cmpl %d1,%d0
jcs L(console_exit)
console_putc #'\n' /* Line wrap using tail recursion */
L(console_exit):
func_return console_putc