Hi,
On Tue, 18 Mar 2008 13:27:09 +0000
Ralf Baechle <ralf@xxxxxxxxxxxxxx> wrote:
> On Tue, Mar 18, 2008 at 01:47:20PM +0900, Yoichi Yuasa wrote:
>
> > On Mon, 17 Mar 2008 16:16:35 +0000
> > Ralf Baechle <ralf@xxxxxxxxxxxxxx> wrote:
> >
> > > On Mon, Mar 17, 2008 at 11:47:40PM +0900, Yoichi Yuasa wrote:
> > >
> > > > VR41xx, CP0 hazard is necessary between read_c0_count() and write_c0_compare().
> > >
> > > Interesting. I wonder why you need this patch but nobody else?
> >
> > Three NOP are necessary on the TB0287(VR4131 board).
>
> That much was obvious from your patch. I was more wondering about this
> change:
>
> - write_c0_compare(read_c0_count());
> + c0_timer_ack();
>
> c0_timer_ack is defined as
>
> static void c0_timer_ack(void)
> {
> write_c0_compare(read_c0_compare());
> }
>
> so your patch does a functional change there - even though it should not
> actually matter. So I was wondering if for some reason you need that
> change.
OK, update my patch.
Two patches have been brought together in one.
How about this?
VR41xx, CP0 hazard is necessary between read_c0_count() and write_c0_compare()
(or read_c0_cause()).
Signed-off-by: Yoichi Yuasa <yoichi_yuasa@xxxxxxxxxxxxxx>
diff -pruN -X /home/yuasa/Memo/dontdiff linux-orig/arch/mips/kernel/cevt-r4k.c linux/arch/mips/kernel/cevt-r4k.c
--- linux-orig/arch/mips/kernel/cevt-r4k.c 2008-03-19 11:35:53.017749179 +0900
+++ linux/arch/mips/kernel/cevt-r4k.c 2008-03-19 16:31:29.617938142 +0900
@@ -186,7 +186,9 @@ static int c0_compare_int_usable(void)
* IP7 already pending? Try to clear it by acking the timer.
*/
if (c0_compare_int_pending()) {
- write_c0_compare(read_c0_count());
+ cnt = read_c0_count();
+ back_to_back_c0_hazard();
+ write_c0_compare(cnt);
irq_disable_hazard();
if (c0_compare_int_pending())
return 0;
@@ -205,10 +207,13 @@ static int c0_compare_int_usable(void)
while ((int)(read_c0_count() - cnt) <= 0)
; /* Wait for expiry */
+ back_to_back_c0_hazard();
if (!c0_compare_int_pending())
return 0;
- write_c0_compare(read_c0_count());
+ cnt = read_c0_count();
+ back_to_back_c0_hazard();
+ write_c0_compare(cnt);
irq_disable_hazard();
if (c0_compare_int_pending())
return 0;
