linux-kernel - Re: [PATCH 2/2] xhci: pci: Put XHCI controllers into D3hot at shutdown

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Message-ID: <20240827063206.GA879539@nchen-desktop>
Date: Tue, 27 Aug 2024 14:32:06 +0800
From: Peter Chen <peter.chen@...nel.org>
To: superm1@...nel.org
Cc: Mathias Nyman <mathias.nyman@...el.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"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 2/2] xhci: pci: Put XHCI controllers into D3hot at
 shutdown

On 24-07-12 13:54:18, superm1@...nel.org wrote:
> From: Mario Limonciello <mario.limonciello@....com>
> 
> A workaround was put in place for Haswell systems with spurious events
> to put XHCI controllers into D3hot at shutdown.  This solution actually
> makes sense for all XHCI controllers though because XHCI controllers
> left in D0 by the OS may remain in D0 when the SoC goes into S5.
> 
> Explicitly put all XHCI controllers into D3hot at shutdown and when
> module is unloaded.
> 
> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
> ---
>  drivers/usb/host/xhci-pci.c | 8 ++------
>  1 file changed, 2 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
> index 4408d4caf66d2..dde5e4a210719 100644
> --- a/drivers/usb/host/xhci-pci.c
> +++ b/drivers/usb/host/xhci-pci.c
> @@ -667,9 +667,7 @@ static void xhci_pci_remove(struct pci_dev *dev)
>  		xhci->shared_hcd = NULL;
>  	}
>  
> -	/* Workaround for spurious wakeups at shutdown with HSW */
> -	if (xhci->quirks & XHCI_SPURIOUS_WAKEUP)
> -		pci_set_power_state(dev, PCI_D3hot);
> +	pci_set_power_state(dev, PCI_D3hot);
>  
>  	usb_hcd_pci_remove(dev);
>  }
> @@ -882,9 +880,7 @@ static void xhci_pci_shutdown(struct usb_hcd *hcd)
>  	xhci_shutdown(hcd);
>  	xhci_cleanup_msix(xhci);
>  
> -	/* Yet another workaround for spurious wakeups at shutdown with HSW */
> -	if (xhci->quirks & XHCI_SPURIOUS_WAKEUP)
> -		pci_set_power_state(pdev, PCI_D3hot);
> +	pci_set_power_state(pdev, PCI_D3hot);

Hi Mario & Mathias,

According to xHCI spec v1.2: A.1.2 Power State Definitions:

	Software shall place each downstream USB port with power
	enabled into the Suspend or Disabled state before it
	attempts to move the xHC out of the D0 power state.

But I have not found any USB core code does it, do you have any ideas
about it?

We have added the similar codes at non-PCI USB platform, but met above
concerns. In fact, we met kernel dump that the thread usb-storage try
to access the port status when the platform xHCI code has already put
the controller to D3.

Best regards,
Peter