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SubjectRe: [PATCH 2/2] net: wwan: iosm: Keep device at D0 for s2idle case
[+cc Rafael, Vaibhav]

On Fri, Dec 24, 2021 at 04:19:14PM +0800, Kai-Heng Feng wrote:
> 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@canonical.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);

This is a weird and non-obvious way to say "this device should stay at
D0". It's also fairly expensive since pci_save_state() does a lot of
slow PCI config reads.

> return 0;
> }
>
> --
> 2.33.1
>

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