[Qemu-devel] [PATCH v2] hw/ptimer: Don't wrap around counter for expired timer that uses tick handler

[Dmitry Osipenko]

Software should see timer counter wrap around only after IRQ being triggered.
Change returned counter value to "1" for the expired timer and avoid returning
wrapped around counter value in periodic mode for the timer that has bottom-half
handler setup, assuming it drives timer IRQ.

This fixes regression introduced by the commit 5a50307 ("hw/ptimer: Perform
counter wrap around if timer already expired") on SPARC emulated machine as
reported by Mark Cave-Ayland.

Signed-off-by: Dmitry Osipenko <dig...@gmail.com>
---
 hw/core/ptimer.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/hw/core/ptimer.c b/hw/core/ptimer.c
index 05b0c27..8006442 100644
--- a/hw/core/ptimer.c
+++ b/hw/core/ptimer.c
@@ -93,10 +93,10 @@ uint64_t ptimer_get_count(ptimer_state *s)
         bool oneshot = (s->enabled == 2);
 
         /* Figure out the current counter value.  */
-        if (s->period == 0 || (expired && (oneshot || use_icount))) {
+        if (expired && (oneshot || use_icount || s->bh != NULL)) {
             /* Prevent timer underflowing if it should already have
                triggered.  */
-            counter = 0;
+            counter = 1;
         } else {
             uint64_t rem;
             uint64_t div;
@@ -143,7 +143,9 @@ uint64_t ptimer_get_count(ptimer_state *s)
 
             if (expired && counter != 0) {
                 /* Wrap around periodic counter.  */
-                counter = s->limit - (counter - 1) % s->limit;
+                counter = s->delta = s->limit - (counter - 1) % s->limit;
+                /* Re-arm timer according to the wrapped around value.  */
+                ptimer_reload(s);
             }
         }
     } else {
-- 
2.9.0