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Date:   Wed, 31 Jul 2019 10:19:58 +0200
From:   Stanislaw Gruszka <sgruszka@redhat.com>
To:     Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Cc:     linux-wireless@vger.kernel.org, Felix Fietkau <nbd@nbd.name>,
        Ryder Lee <ryder.lee@mediatek.com>, Roy Luo <royluo@google.com>
Subject: Re: [RFC] mt76: fix tx hung regression on MT7630E
Message-ID: <20190731081957.GA4096@redhat.com>
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On Tue, Jul 30, 2019 at 04:55:31PM +0200, Lorenzo Bianconi wrote:
> > > > 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);
> > > 
> > > I am not sure if we really need mt76x02_mac_poll_tx_status() here since we run
> > > it in mt76x02_tx_complete_skb() and in mt76x02_tx_tasklet(). Anyway the only
> > > difference doing so is we do not run mt76x02_send_tx_status().
> > 
> > I thought this is the problem, but it was my mistake during testing.
> > I tested the above change together with mt76_txq_schedule(dev, txq->ac)
> > change and get wrong impression it fixes the issue. But above change
> > alone does not help.
> > 
> > I tried to add some locking to avoid parallel execution of mt76x02_poll_tx()
> > and mt76x02_tx_tasklet(), but it didn't help either. So far only patch
> > originally posted here make the problem gone.
> 
> so, in order to be on the same page, if you comment out mt76x02_mac_poll_tx_status()
> in mt76x02_poll_tx() the issue will still occur. The only to 'fix' it is to run
> mt76_txq_schedule_all() in mt76x02_poll_tx(), right?

Yes.

Stanislaw