Re: Keyboard lockup with NetBSD5

["Michael L. Hitch" <mhitch%NetBSD.org@localhost>]

On Mon, 16 Nov 2009, Frank Wille wrote:

> The following patch makes delay() work (for keyboard and floppy disk):
>
> RCS file: /cvsroot/src/sys/arch/amiga/dev/clock.c,v
> retrieving revision 1.50
> diff -r1.50 clock.c
> 697c697
> <                       remaining -= amiga_clk_interval - (cur_tick -
> initial_tick);
> ---
> >                       remaining -= cur_tick - initial_tick;
> 699c699
> <                       remaining -= initial_tick - cur_tick;
> ---
> >                       remaining -= amiga_clk_interval - (initial_tick -
> cur_tick);

  I'm not certain that this patch is entirely correct, if I understand it
properly (no guarantee that I'm not missing something).  Most of the time
in the while() loop, cur_tick will be equal to initial_tick, and it will
subtract amiga_clk_interval from remaining each time through the loop
and delay() will exit very quickly.  Was this the patch that worked on the
A1200?

  I would thing that this would be a better change:

Index: sys/arch/amiga/dev/clock.c
===================================================================
RCS file: /cvsroot/src/sys/arch/amiga/dev/clock.c,v
retrieving revision 1.50
diff -u -p -r1.50 clock.c
--- sys/arch/amiga/dev/clock.c  11 Sep 2009 19:43:08 -0000      1.50
+++ sys/arch/amiga/dev/clock.c  26 Nov 2009 17:35:26 -0000
@@ -693,10 +693,10 @@ delay(unsigned int n)

        while (remaining > 0) {
                cur_tick = clk_gettick();
-               if (cur_tick > initial_tick)
-                       remaining -= amiga_clk_interval - (cur_tick - 
initial_tick);
+               if (cur_tick >= initial_tick)
+                       remaining -= cur_tick - initial_tick;
                else
-                       remaining -= initial_tick - cur_tick;
+                       remaining -= amiga_clk_interval - (initial_tick - 
cur_tick);
                initial_tick = cur_tick;
        }
 }

  With this patch, most of the time in the loop will be subtracting 0 from
remaining.  Every time the hardware counter decrement, it would then
subtract 1 from remaining [presuming the loop hasn't been interrupted,
otherwise it would subtract a larger amount].  And every 100 milliseconds,
the other subtraction would occur.