From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1EB30C433FF for ; Mon, 29 Jul 2019 12:53:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F2A34206DD for ; Mon, 29 Jul 2019 12:53:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727301AbfG2Mx5 (ORCPT ); Mon, 29 Jul 2019 08:53:57 -0400 Received: from mx1.redhat.com ([209.132.183.28]:35946 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727172AbfG2Mx5 (ORCPT ); Mon, 29 Jul 2019 08:53:57 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D1F0C307D868; Mon, 29 Jul 2019 12:53:56 +0000 (UTC) Received: from localhost (unknown [10.43.2.114]) by smtp.corp.redhat.com (Postfix) with ESMTP id 929EE60C44; Mon, 29 Jul 2019 12:53:53 +0000 (UTC) Date: Mon, 29 Jul 2019 14:53:51 +0200 From: Stanislaw Gruszka To: linux-wireless@vger.kernel.org Cc: Felix Fietkau , Lorenzo Bianconi , Ryder Lee , Roy Luo Subject: Re: [RFC] mt76: fix tx hung regression on MT7630E Message-ID: <20190729125351.GA3086@redhat.com> References: <1564143056-14610-1-git-send-email-sgruszka@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1564143056-14610-1-git-send-email-sgruszka@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Mon, 29 Jul 2019 12:53:56 +0000 (UTC) Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org On Fri, Jul 26, 2019 at 02:10:56PM +0200, Stanislaw Gruszka wrote: > Since 41634aa8d6db ("mt76: only schedule txqs from the tx tasklet") > I can observe firmware hangs on MT7630E on station mode: tx stop > functioning after minor activity (rx keep working) and on module > unload device fail to stop with messages: > > [ 5446.141413] mt76x0e 0000:06:00.0: TX DMA did not stop > [ 5449.176764] mt76x0e 0000:06:00.0: TX DMA did not stop > > Loading module again results in failure to associate with AP. > Only machine power off / power on cycle can make device work again. > > I have no idea why the commit caused F/W hangs. Most likely some proper > fix is needed of changing registers programming (or assuring proper order > of actions), but so far I can not came up with any better fix than > a partial revert of 41634aa8d6db. The difference is that with 41634aa8d6db we can run mt76x02_poll_tx() and mt76x02_tx_tasklet() in parallel on 2 different CPUs. Without the commit, since tasklet is not scheduled from mt76_wake_tx_queue(), it does not happen. I'm not quite sure why, but MT7630E does not like when we poll tx status on 2 cpus at once. Change like below: diff --git a/drivers/net/wireless/mediatek/mt76/mt76x02_mmio.c b/drivers/net/wireless/mediatek/mt76/mt76x02_mmio.c index 467b28379870..622251faa415 100644 --- a/drivers/net/wireless/mediatek/mt76/mt76x02_mmio.c +++ b/drivers/net/wireless/mediatek/mt76/mt76x02_mmio.c @@ -170,7 +170,7 @@ static int mt76x02_poll_tx(struct napi_struct *napi, int budget) mt76.tx_napi); int i; - mt76x02_mac_poll_tx_status(dev, false); + mt76x02_mac_poll_tx_status(dev, true); for (i = MT_TXQ_MCU; i >= 0; i--) mt76_queue_tx_cleanup(dev, i, false); is sufficient to avoid the hangs. > diff --git a/drivers/net/wireless/mediatek/mt76/tx.c b/drivers/net/wireless/mediatek/mt76/tx.c > index 5397827668b9..fefe0ee52584 100644 > --- a/drivers/net/wireless/mediatek/mt76/tx.c > +++ b/drivers/net/wireless/mediatek/mt76/tx.c > @@ -598,7 +598,7 @@ void mt76_wake_tx_queue(struct ieee80211_hw *hw, struct ieee80211_txq *txq) > if (!test_bit(MT76_STATE_RUNNING, &dev->state)) > return; > > - tasklet_schedule(&dev->tx_tasklet); > + mt76_txq_schedule(dev, txq->ac); However I'm not sure if change to tasklet_schedule() is indeed correct, since on tasklet we schedule all queues, hence queues that could possibly be still blocked? And on mt76_wake_tx_queue() we schedule only one queue. Stanislaw