Re: [PATCH] mt76: mt7921: fix possible resume failure

From: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
To: sean.wang@mediatek.com
Cc: nbd@nbd.name, Soul.Huang@mediatek.com, YN.Chen@mediatek.com,
	Leon.Yen@mediatek.com, Eric-SY.Chang@mediatek.com,
	Mark-YW.Chen@mediatek.com, Deren.Wu@mediatek.com,
	km.lin@mediatek.com, robin.chiu@mediatek.com,
	Eddie.Chen@mediatek.com, ch.yeh@mediatek.com,
	posh.sun@mediatek.com, ted.huang@mediatek.com,
	Eric.Liang@mediatek.com, Stella.Chang@mediatek.com,
	Tom.Chou@mediatek.com, steve.lee@mediatek.com, jsiuda@google.com,
	frankgor@google.com, jemele@google.com,
	abhishekpandit@google.com, shawnku@google.com,
	linux-wireless@vger.kernel.org,
	linux-mediatek@lists.infradead.org
Subject: Re: [PATCH] mt76: mt7921: fix possible resume failure
Date: Tue, 7 Dec 2021 21:08:04 +0100	[thread overview]
Message-ID: <Ya+/JNMaq2O3BKwb@lore-desk> (raw)
In-Reply-To: <1638897717-14465-1-git-send-email-sean.wang@mediatek.com>

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> From: Sean Wang <sean.wang@mediatek.com>
> 
> >> From: Sean Wang <sean.wang@mediatek.com>
> >>
> >> Fix the possible resume failure due to mt76_connac_mcu_set_hif_suspend
> >> timeout.
> >>
> >> That is because clearing the flag pm->suspended too early opened up a
> >> race window, where mt7921_poll_tx/rx scheduled a ps_work to put the
> >> device in doze mode, that is unexpected for the device is being
> >> resumed from the suspend state and would make the remaining MCU
> >> comamnds in resume handler failed to execute.
> >
> >do we have a similar issue in mt7921s_resume()?
> 
> We don't have the same issue found in mt7921s_resume because the driver
> guarantees all MCU commands (even in mt7921s_resume) always work in the active
> state.
> 
> But we can have the same patch for mt7921s just to make code consistent with
> mt7921e.

ack, agree.

Regards,
Lorenzo

> 
> >
> >>
> >> Fixes: ffa1bf97425b ("mt76: mt7921: introduce PM support")
> >> Co-developed-by: YN Chen <YN.Chen@mediatek.com>
> >> Signed-off-by: YN Chen <YN.Chen@mediatek.com>
> >> Signed-off-by: Sean Wang <sean.wang@mediatek.com>
> >> ---
> >>  drivers/net/wireless/mediatek/mt76/mt7921/pci.c | 7 +++++--
> >>  1 file changed, 5 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/pci.c
> >> b/drivers/net/wireless/mediatek/mt76/mt7921/pci.c
> >> index 5635de3c80b1..21a48f02ab60 100644
> >> --- a/drivers/net/wireless/mediatek/mt76/mt7921/pci.c
> >> +++ b/drivers/net/wireless/mediatek/mt76/mt7921/pci.c
> >> @@ -315,7 +315,6 @@ static int mt7921_pci_resume(struct pci_dev *pdev)
> >>	struct mt76_connac_pm *pm = &dev->pm;
> >>	int i, err;
> >>
> >> -	pm->suspended = false;
> >>	err = pci_set_power_state(pdev, PCI_D0);
> >>	if (err)
> >>		return err;
> >> @@ -353,7 +352,11 @@ static int mt7921_pci_resume(struct pci_dev *pdev)
> >>	if (!pm->ds_enable)
> >>		mt76_connac_mcu_set_deep_sleep(&dev->mt76, false);
> >>
> >> -	return mt76_connac_mcu_set_hif_suspend(mdev, false);
> >> +	err = mt76_connac_mcu_set_hif_suspend(mdev, false);
> >> +
> >> +	pm->suspended = false;
> >> +
> >> +	return err;
> >>  }
> >>  #endif /* CONFIG_PM */
> >>
> >> --
> >> 2.25.1
> >>
> >
> 

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