From patchwork Thu Jan 20 00:36:44 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Miquel Raynal X-Patchwork-Id: 533813 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DBA3DC4332F for ; Thu, 20 Jan 2022 00:37:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1357900AbiATAhJ (ORCPT ); Wed, 19 Jan 2022 19:37:09 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42288 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1357894AbiATAhE (ORCPT ); Wed, 19 Jan 2022 19:37:04 -0500 Received: from relay6-d.mail.gandi.net (relay6-d.mail.gandi.net [IPv6:2001:4b98:dc4:8::226]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5F1FBC06173F; Wed, 19 Jan 2022 16:37:03 -0800 (PST) Received: (Authenticated sender: miquel.raynal@bootlin.com) by mail.gandi.net (Postfix) with ESMTPSA id 7619EC0004; Thu, 20 Jan 2022 00:37:00 +0000 (UTC) From: Miquel Raynal To: Alexander Aring , Stefan Schmidt , linux-wpan@vger.kernel.org Cc: "David S. Miller" , Jakub Kicinski , netdev@vger.kernel.org, linux-wireless@vger.kernel.org, Xue Liu , Marcel Holtmann , Harry Morris , David Girault , Romuald Despres , Frederic Blain , Nicolas Schodet , Thomas Petazzoni , Miquel Raynal Subject: [wpan-next 8/9] net: mac802154: Explain the use of ieee802154_wake/stop_queue() Date: Thu, 20 Jan 2022 01:36:44 +0100 Message-Id: <20220120003645.308498-9-miquel.raynal@bootlin.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20220120003645.308498-1-miquel.raynal@bootlin.com> References: <20220120003645.308498-1-miquel.raynal@bootlin.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org 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 --- include/net/mac802154.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) 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);