[v3,16/41] net: mac802154: Explain the use of ieee802154_wake/stop_queue()

Commit Message

Miquel Raynal Jan. 17, 2022, 11:54 a.m. UTC

It is not straightforward to the newcomer that a single skb can be sent
at a time and that the internal process is to stop the queue when
processing a frame before re-enabling it. Make this clear by documenting
the ieee802154_wake/stop_queue() helpers.

Signed-off-by: Miquel Raynal <[e-mail]>
---
 include/net/mac802154.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

Patch

diff --git a/include/net/mac802154.h b/include/net/mac802154.h
index d524ffb9eb25..94b2e3008e77 100644
--- a/include/net/mac802154.h
+++ b/include/net/mac802154.h
@@ -464,6 +464,12 @@  void ieee802154_rx_irqsafe(struct ieee802154_hw *hw, struct sk_buff *skb,
  * ieee802154_wake_queue - wake ieee802154 queue
  * @hw: pointer as obtained from ieee802154_alloc_hw().
  *
+ * Tranceivers have either one transmit framebuffer or one framebuffer for both
+ * transmitting and receiving. Hence, the core only handles one frame at a time
+ * for each phy, which means we had to stop the queue to avoid new skb to come
+ * during the transmission. The queue then needs to be woken up after the
+ * operation.
+ *
  * Drivers should use this function instead of netif_wake_queue.
  */
 void ieee802154_wake_queue(struct ieee802154_hw *hw);
@@ -472,6 +478,12 @@  void ieee802154_wake_queue(struct ieee802154_hw *hw);
  * ieee802154_stop_queue - stop ieee802154 queue
  * @hw: pointer as obtained from ieee802154_alloc_hw().
  *
+ * Tranceivers have either one transmit framebuffer or one framebuffer for both
+ * transmitting and receiving. Hence, the core only handles one frame at a time
+ * for each phy, which means we need to tell upper layers to stop giving us new
+ * skbs while we are busy with the transmitted one. The queue must then be
+ * stopped before transmitting.
+ *
  * Drivers should use this function instead of netif_stop_queue.
  */
 void ieee802154_stop_queue(struct ieee802154_hw *hw);