From:   <sean.wang@mediatek.com>
To:     <lorenzo.bianconi@redhat.com>
CC:     <nbd@nbd.name>, <sean.wang@mediatek.com>,
        <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:   Wed, 8 Dec 2021 01:21:57 +0800
Message-ID: <1638897717-14465-1-git-send-email-sean.wang@mediatek.com>
In-Reply-To: <Ya8ysehFjoEGGEf+@lore-desk--annotate>
References: <Ya8ysehFjoEGGEf+@lore-desk--annotate>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

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.

>
>>
>> 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
>>
>