mach64: fix cursor when character width is not a multiple of 8 pixels

This patch fixes the hardware cursor on mach64 when font width is not a
multiple of 8 pixels.

If you load such a font, the cursor is expanded to the next 8-byte
boundary and a part of the next character after the cursor is not
visible.
For example, when you load a font with 12-pixel width, the cursor width
is 16 pixels and when the cursor is displayed, 4 pixels of the next
character are not visible.

The reason is this: atyfb_cursor is called with proper parameters to
load an image that is 12-pixel wide. However, the number is aligned on
the next 8-pixel boundary on the line
"unsigned int width = (cursor->image.width + 7) >> 3;" and the whole
function acts as it is was loading a 16-pixel image.

This patch fixes it so that the value written to the framebuffer is
padded with 0xaaaa (the transparent pattern) when the image size it not
a multiple of 8 pixels. The transparent pattern causes that the cursor
will not interfere with the next character.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

diff --git a/drivers/video/aty/mach64_cursor.c b/drivers/video/aty/mach64_cursor.c
index 95ec042..0fe02e2 100644 (file)
--- a/drivers/video/aty/mach64_cursor.c
+++ b/drivers/video/aty/mach64_cursor.c
@@ -5,6 +5,7 @@
 #include <linux/fb.h>
 #include <linux/init.h>
 #include <linux/string.h>
+#include "../fb_draw.h"
 
 #include <asm/io.h>
 
@@ -157,24 +158,33 @@ static int atyfb_cursor(struct fb_info *info, struct fb_cursor *cursor)
 
            for (i = 0; i < height; i++) {
                for (j = 0; j < width; j++) {
+                       u16 l = 0xaaaa;
                        b = *src++;
                        m = *msk++;
                        switch (cursor->rop) {
                        case ROP_XOR:
                            // Upper 4 bits of mask data
-                           fb_writeb(cursor_bits_lookup[(b ^ m) >> 4], dst++);
+                           l = cursor_bits_lookup[(b ^ m) >> 4] |
                            // Lower 4 bits of mask
-                           fb_writeb(cursor_bits_lookup[(b ^ m) & 0x0f],
-                                     dst++);
+                                   (cursor_bits_lookup[(b ^ m) & 0x0f] << 8);
                            break;
                        case ROP_COPY:
                            // Upper 4 bits of mask data
-                           fb_writeb(cursor_bits_lookup[(b & m) >> 4], dst++);
+                           l = cursor_bits_lookup[(b & m) >> 4] |
                            // Lower 4 bits of mask
-                           fb_writeb(cursor_bits_lookup[(b & m) & 0x0f],
-                                     dst++);
+                                   (cursor_bits_lookup[(b & m) & 0x0f] << 8);
                            break;
                        }
+                       /*
+                        * If cursor size is not a multiple of 8 characters
+                        * we must pad it with transparent pattern (0xaaaa).
+                        */
+                       if ((j + 1) * 8 > cursor->image.width) {
+                               l = comp(l, 0xaaaa,
+                                   (1 << ((cursor->image.width & 7) * 2)) - 1);
+                       }
+                       fb_writeb(l & 0xff, dst++);
+                       fb_writeb(l >> 8, dst++);
                }
                dst += offset;
            }