linux-kernel - Re: [PATCH 1/2] xhci: pci: If no ports have wakeup enabled then disable PCI device at S4

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Message-ID: <76daeba0-ac1a-4e05-8d25-3966526b464e@linux.intel.com>
Date: Wed, 21 Aug 2024 12:25:36 +0300
From: Mathias Nyman <mathias.nyman@...ux.intel.com>
To: superm1@...nel.org, Mathias Nyman <mathias.nyman@...el.com>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: "open list:USB XHCI DRIVER" <linux-usb@...r.kernel.org>,
 open list <linux-kernel@...r.kernel.org>,
 Kai-Heng Feng <kai.heng.feng@...onical.com>,
 mika.westerberg@...ux.intel.com,
 Mario Limonciello <mario.limonciello@....com>
Subject: Re: [PATCH 1/2] xhci: pci: If no ports have wakeup enabled then
 disable PCI device at S4

On 12.7.2024 21.54, superm1@...nel.org wrote:
> From: Mario Limonciello <mario.limonciello@....com>
> 
> If a port on an XHCI controller hasn't been marked for wakeup at S4, then
> leaving it at D0 will needlessly consume power than necessary.
> 
> Explicitly check ports configured for wakeup and if none are found then
> put the controller into D3hot before hibernate.
> 
> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
> ---
>   drivers/usb/host/xhci-pci.c | 9 +++++++++
>   1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
> index 05881153883ec..4408d4caf66d2 100644
> --- a/drivers/usb/host/xhci-pci.c
> +++ b/drivers/usb/host/xhci-pci.c
> @@ -823,6 +823,7 @@ static int xhci_pci_poweroff_late(struct usb_hcd *hcd, bool do_wakeup)
>   	struct usb_device	*udev;
>   	u32			portsc;
>   	int			i;
> +	bool			wakeup = false;
>   
>   	/*
>   	 * Systems with XHCI_RESET_TO_DEFAULT quirk have boot firmware that
> @@ -860,6 +861,14 @@ static int xhci_pci_poweroff_late(struct usb_hcd *hcd, bool do_wakeup)
>   			 port->rhub->hcd->self.busnum, port->hcd_portnum + 1);
>   		portsc = xhci_port_state_to_neutral(portsc);
>   		writel(portsc | PORT_PE, port->addr);
> +		wakeup = true;
> +	}
> +
> +	if (!wakeup) {
> +		struct pci_dev *pdev = to_pci_dev(hcd->self.controller);
> +
> +		xhci_shutdown(hcd);
> +		pci_set_power_state(pdev, PCI_D3hot);

Not sure we should force D3 here.
I think usb core will set the PCI D state in the next .poweroff_noirq stage,

for s4:
.poweroff	= hcd_pci_suspend,
.poweroff_late	= hcd_pci_poweroff_late,
.poweroff_noirq	= hcd_pci_suspend_noirq,

hcd_pci_suspend_noirq()
   pci_prepare_to_sleep();
     target_state = pci_target_state(dev, wakeup)
     pci_set_power_state(dev, target_state)

Maybe the target_state isn't D3 for some reason? (missing ACPI entries?)

Thanks
Mathias