linux-kernel - [PATCH v2] rtw88: pci: Power cycle device during shutdown

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Message-Id: <20200928165508.20775-1-kai.heng.feng@canonical.com>
Date:   Tue, 29 Sep 2020 00:55:08 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     yhchuang@...ltek.com, kvalo@...eaurora.org
Cc:     briannorris@...omium.org,
        Kai-Heng Feng <kai.heng.feng@...onical.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        linux-wireless@...r.kernel.org (open list:REALTEK WIRELESS DRIVER
        (rtw88)), netdev@...r.kernel.org (open list:NETWORKING DRIVERS),
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH v2] rtw88: pci: Power cycle device during shutdown

There are reports that 8822CE fails to work rtw88 with "failed to read DBI
register" error. Also I have a system with 8723DE which freezes the whole
system when the rtw88 is probing the device.

According to [1], platform firmware may not properly power manage the
device during shutdown. I did some expirements and putting the device to
D3 can workaround the issue.

So let's power cycle the device by putting the device to D3 at shutdown
to prevent the issue from happening.

[1] https://bugzilla.kernel.org/show_bug.cgi?id=206411#c9

BugLink: https://bugs.launchpad.net/bugs/1872984
Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
---
v2:
 - Add more detail in commit log.

 drivers/net/wireless/realtek/rtw88/pci.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/wireless/realtek/rtw88/pci.c b/drivers/net/wireless/realtek/rtw88/pci.c
index 3413973bc475..7f1f5073b9f4 100644
--- a/drivers/net/wireless/realtek/rtw88/pci.c
+++ b/drivers/net/wireless/realtek/rtw88/pci.c
@@ -1599,6 +1599,8 @@ void rtw_pci_shutdown(struct pci_dev *pdev)
 
 	if (chip->ops->shutdown)
 		chip->ops->shutdown(rtwdev);
+
+	pci_set_power_state(pdev, PCI_D3hot);
 }
 EXPORT_SYMBOL(rtw_pci_shutdown);
 
-- 
2.17.1