netdev - [PATCH 2/2] net: wwan: iosm: Keep device at D0 for s2idle case

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Date:   Fri, 24 Dec 2021 16:19:14 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     m.chetan.kumar@...el.com, linuxwwan@...el.com
Cc:     linux-pci@...r.kernel.org, linux-pm@...r.kernel.org,
        Kai-Heng Feng <kai.heng.feng@...onical.com>,
        Loic Poulain <loic.poulain@...aro.org>,
        Sergey Ryazanov <ryazanov.s.a@...il.com>,
        Johannes Berg <johannes@...solutions.net>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] net: wwan: iosm: Keep device at D0 for s2idle case

We are seeing spurious wakeup caused by Intel 7560 WWAN on AMD laptops.
This prevent those laptops to stay in s2idle state.

>From what I can understand, the intention of ipc_pcie_suspend() is to
put the device to D3cold, and ipc_pcie_suspend_s2idle() is to keep the
device at D0. However, the device can still be put to D3hot/D3cold by
PCI core.

So explicitly let PCI core know this device should stay at D0, to solve
the spurious wakeup.

Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
---
 drivers/net/wwan/iosm/iosm_ipc_pcie.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/wwan/iosm/iosm_ipc_pcie.c b/drivers/net/wwan/iosm/iosm_ipc_pcie.c
index d73894e2a84ed..af1d0e837fe99 100644
--- a/drivers/net/wwan/iosm/iosm_ipc_pcie.c
+++ b/drivers/net/wwan/iosm/iosm_ipc_pcie.c
@@ -340,6 +340,9 @@ static int __maybe_unused ipc_pcie_suspend_s2idle(struct iosm_pcie *ipc_pcie)
 
 	ipc_imem_pm_s2idle_sleep(ipc_pcie->imem, true);
 
+	/* Let PCI core know this device should stay at D0 */
+	pci_save_state(ipc_pcie->pci);
+
 	return 0;
 }
 
-- 
2.33.1