[S390] qdio: move ACK to newest buffer for devices without QEBSM

The ACKnowledgement state should be set on the newest SBAL so an
adapter interrupt surpression check needs to scan fewer SBALs.

Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 8 insertions, 5 deletions

diff --git a/drivers/s390/cio/qdio_main.c b/drivers/s390/cio/qdio_main.c
index 8e6bc9cddfa0..61ba765936a6 100644
--- a/drivers/s390/cio/qdio_main.c
+++ b/drivers/s390/cio/qdio_main.c
@@ -440,12 +440,16 @@ static inline void inbound_primed(struct qdio_q *q, int count)
                 /* reset the previous ACK but first set the new one */
                 set_buf_state(q, new, SLSB_P_INPUT_ACK);
                 set_buf_state(q, q->last_move_ftc, SLSB_P_INPUT_NOT_INIT);
-        }
-        else {
+        } else {
                 q->u.in.polling = 1;
-                set_buf_state(q, q->first_to_check, SLSB_P_INPUT_ACK);
+                set_buf_state(q, new, SLSB_P_INPUT_ACK);
         }
 
+        /*
+         * last_move_ftc points to the ACK'ed buffer and not to the last turns
+         * first_to_check like for qebsm. Since it is only used to check if
+         * the queue front moved in qdio_inbound_q_done this is not a problem.
+         */
         q->last_move_ftc = new;
         count--;
         if (!count)
@@ -455,7 +459,7 @@ static inline void inbound_primed(struct qdio_q *q, int count)
          * Need to change all PRIMED buffers to NOT_INIT, otherwise
          * we're loosing initiative in the thinint code.
          */
-        set_buf_states(q, next_buf(q->first_to_check), SLSB_P_INPUT_NOT_INIT,
+        set_buf_states(q, q->first_to_check, SLSB_P_INPUT_NOT_INIT,
                        count);
 }
 
@@ -1480,7 +1484,6 @@ static void handle_inbound(struct qdio_q *q, unsigned int callflags,
                         if (q->u.in.ack_count <= 0) {
                                 q->u.in.polling = 0;
                                 q->u.in.ack_count = 0;
-                                /* TODO: must we set last_move_ftc to something meaningful? */
                                 goto set;
                         }
                         q->last_move_ftc = add_buf(q->last_move_ftc, diff);