This patch optimizes implementation of iwl_queue_inc_wrap and
iwl_queue_inc_wrap based on the fact the hardware queue is power-of-two
size. We also add BUG_ON and BUILD_BUG_ON check for queue size against
is_power_of_2 in case future hardwares break this rule.
Signed-off-by: Zhu Yi <yi.zhu@xxxxxxxxx>
---
drivers/net/wireless/iwl-base.c | 16 +++++++++++++---
1 files changed, 13 insertions(+), 3 deletions(-)
diff --git a/drivers/net/wireless/iwl-base.c b/drivers/net/wireless/iwl-base.c
index 4d73b86..becaeea 100644
--- a/drivers/net/wireless/iwl-base.c
+++ b/drivers/net/wireless/iwl-base.c
@@ -160,14 +160,16 @@ static int iwl_queue_space(const struct iwl_queue *q)
return s;
}
+/* XXX: n_bd must be power-of-two size */
static inline int iwl_queue_inc_wrap(int index, int n_bd)
{
- return (++index == n_bd) ? 0 : index;
+ return ++index & (n_bd - 1);
}
+/* XXX: n_bd must be power-of-two size */
static inline int iwl_queue_dec_wrap(int index, int n_bd)
{
- return (index == 0) ? n_bd - 1 : index - 1;
+ return --index & (n_bd - 1);
}
static inline int x2_queue_used(const struct iwl_queue *q, int i)
@@ -192,6 +194,10 @@ static int iwl_queue_init(struct iwl_priv *priv, struct iwl_queue *q,
q->n_window = slots_num;
q->id = id;
+ /* count must be power-of-two size, otherwise iwl_queue_inc_wrap
+ * and iwl_queue_dec_wrap are broken. */
+ BUG_ON(!is_power_of_2(count));
+
q->low_mark = q->n_window / 4;
if (q->low_mark < 4)
q->low_mark = 4;
@@ -266,9 +272,13 @@ int iwl_tx_queue_init(struct iwl_priv *priv,
return -ENOMEM;
}
-
txq->need_update = 0;
+
+ /* TFD_QUEUE_SIZE_MAX must be power-of-two size, otherwise
+ * iwl_queue_inc_wrap and iwl_queue_dec_wrap are broken. */
+ BUILD_BUG_ON(TFD_QUEUE_SIZE_MAX & (TFD_QUEUE_SIZE_MAX - 1));
iwl_queue_init(priv, &txq->q, TFD_QUEUE_SIZE_MAX, slots_num, txq_id);
+
iwl_hw_tx_queue_init(priv, txq);
return 0;
--
1.5.2
-
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