video: fbdev: amifb: add FIXME about dead APUS support

On 5/14/20 10:21 PM, Geert Uytterhoeven wrote:

> These #ifdefs are relics from APUS (Amiga Power-Up System), which
> added a PPC board.  APUS support was killed off a long time ago,
> when arch/ppc/ was still king, but these #ifdefs were missed, because
> they didn't test for CONFIG_APUS.

Add FIXME about using the C code variants (APUS ones) in the future.
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/767d36ff-22ec-8136-7ebc-1d9d0d3ac98d@samsung.com

drivers/video/fbdev/amifb.c

@@ -575,6 +575,12 @@ static u_short maxfmode, chipset;
 #define downx(x, v)	((v) & -(x))
 #define modx(x, v)	((v) & ((x) - 1))
 
+/*
+ * FIXME: Use C variants of the code marked with #ifdef __mc68000__
+ * in the driver. It shouldn't negatively affect the performance and
+ * is required for APUS support (once it is re-added to the kernel).
+ * Needs to be tested on the hardware though..
+ */
 /* if x1 is not a constant, this macro won't make real sense :-) */
 #ifdef __mc68000__
 #define DIVUL(x1, x2) ({int res; asm("divul %1,%2,%3": "=d" (res): \