Re: [PATCH v2] Bluetooth: Properly disable remote wakeup for MT7922/MT7925 on Ryzen platform

[Rong Zhang <i@rong.moe>]

Hi Luiz,

On Tue, 2026-09-01 at 13:05 -0400, Luiz Augusto von Dentz wrote:
> Hi Rong,
> 
> On Tue, Sep 1, 2026 at 12:42 PM Rong Zhang <i@rong.moe> wrote:
> > 
> > Hi Luiz,
> > 
> > Gentle ping.
> > 
> > On Wed, 2026-07-01 at 23:43 +0800, Rong Zhang wrote:
> > > It is reported that a remote wakeup could cause MT7922/MT7925's btusb
> > > interface completely unresponsive. Resetting the xHCI root hub doesn't
> > > help at all, and recovering from such a state needs a power cycle.
> > > 
> > > All reports seen to be relevant to Ryzen-based laptops. These NICs are
> > > usually used as OEM components thanks to some sort of reference designs.
> > > Their popularity on other platforms is unclear. While there is still a
> > > chance that the quirk may exist on other platforms, be cautious and only
> > > apply the quirk to direct children of Ryzen platforms's root hubs for
> > > the time being. In most cases the root hub is on the SoC or PCH, which
> > > needs the quirk. Unfortunately, this can't distinguish root hubs on PCIe
> > > add-in cards. Such roughness should be acceptable, as PCIe USB
> > > controller add-in cards are less commonly used nowadays. On the other
> > > hand, applying the quirk doesn't hurt any functionalities either, as the
> > > device can still be used as a wakeup source if desired. Theoretically,
> > > we could retrieve the root hub's PCI vendor ID with some hierarchy
> > > magic, but that's too intrusive...
> > > 
> > > Meanwhile, though device_set_wakeup_capable(false) is the correct fix
> > > for other NICs with fake remote wakeup capabilities, doing so for
> > > MT7922/MT7925 effectively prevents it from being used as wakeup
> > > sources as per userspace requests. Hence, return -EBUSY on runtime
> > > suspend to prevent the interface from being autosuspended while it's
> > > still opened, which has the same effect as
> > > device_set_wakeup_capable(false), since disabling remote wakeup simply
> > > causes the USB core to gate runtime autosuspend as well due to
> > > needs_remote_wakeup == 1. The interface can be safely autosuspended as
> > > long as remote wakeup is disabled, i.e., after closing the HCI device.
> > > 
> > > Specifically, the interface may still take the advantage of remote
> > > wakeup in order to wake up the system from sleep if userspace has
> > > enabled it as a wakeup source.
> > > 
> > > Fixes: e31d761628ad ("Bluetooth: btmtk: Disable remote wakeup for MT7922/MT7925")
> > > Signed-off-by: Rong Zhang <i@rong.moe>
> > 
> > Could you kindly take a look at the patch?
> > 
> > Chris Lu from MediaTek has relied with a "LGTM" to the patch, and there
> > is already a Tested-by from Rafael Passos. Additionally, based on
> > Rafael's debugging observations, the issue does exist on AMD PCHs, so
> > matching X86_FEATURE_ZEN is appropriate.
> 
> Please resubmit so it can be retested, since it has already been
> archived for being over 30 days old.

Thanks for the reminder. Will resubmit it soon.

Thanks,
Rong

> 
> > Thanks,
> > Rong
> > 
> > > ---
> > > Changes in v2:
> > > - Only apply the quirk to to direct children of Ryzen platforms's root
> > >   hubs
> > >   - Theoretically, we could retrieve the root hub's PCI vendor ID with
> > >     some hierarchy magic to further limit the range down to only root
> > >     hubs on the SoC or PCH, but that's too intrusive -- the hierarchy
> > >     magic really made me nervous once I saw what I have wrote, so I gave
> > >     it up
> > > - Link to v1: https://patch.msgid.link/20260629-btmtk-ryzen-remote-wakeup-v1-1-1d2f1cee6d22@rong.moe
> > > ---
> > >  drivers/bluetooth/btmtk.c | 10 -------
> > >  drivers/bluetooth/btusb.c | 73 ++++++++++++++++++++++++++++++++++++++++++++---
> > >  2 files changed, 69 insertions(+), 14 deletions(-)
> > > 
> > > diff --git a/drivers/bluetooth/btmtk.c b/drivers/bluetooth/btmtk.c
> > > index 02a96342e964..4614434dd57b 100644
> > > --- a/drivers/bluetooth/btmtk.c
> > > +++ b/drivers/bluetooth/btmtk.c
> > > @@ -1381,16 +1381,6 @@ int btmtk_usb_setup(struct hci_dev *hdev)
> > >               break;
> > >       case 0x7922:
> > >       case 0x7925:
> > > -             /*
> > > -              * A remote wakeup could cause the device completely unresponsive, and
> > > -              * recovering from such a state needs a power cycle.
> > > -              *
> > > -              * Since the remote wakeup capability is super broken, just disable it
> > > -              * to get rid of the troubles. The device can still be autosuspended
> > > -              * when the bluetooth interface is closed.
> > > -              */
> > > -             device_set_wakeup_capable(&btmtk_data->udev->dev, false);
> > > -             fallthrough;
> > >       case 0x7961:
> > >       case 0x7902:
> > >       case 0x6639:
> > > diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
> > > index 08c0a99a62c5..eef6e3b43bf9 100644
> > > --- a/drivers/bluetooth/btusb.c
> > > +++ b/drivers/bluetooth/btusb.c
> > > @@ -6,6 +6,7 @@
> > >   *  Copyright (C) 2005-2008  Marcel Holtmann <marcel@holtmann.org>
> > >   */
> > > 
> > > +#include <linux/cpufeature.h>
> > >  #include <linux/dmi.h>
> > >  #include <linux/module.h>
> > >  #include <linux/usb.h>
> > > @@ -957,6 +958,7 @@ struct qca_dump_info {
> > >  #define BTUSB_USE_ALT3_FOR_WBS       15
> > >  #define BTUSB_ALT6_CONTINUOUS_TX     16
> > >  #define BTUSB_HW_SSR_ACTIVE  17
> > > +#define BTUSB_WAKEUP_BROKEN  18
> > > 
> > >  struct btusb_data {
> > >       struct hci_dev       *hdev;
> > > @@ -2936,10 +2938,25 @@ static int btusb_send_frame_mtk(struct hci_dev *hdev, struct sk_buff *skb)
> > >       }
> > >  }
> > > 
> > > +static inline bool platform_is_ryzen(void)
> > > +{
> > > +#ifdef CONFIG_X86
> > > +     return boot_cpu_has(X86_FEATURE_ZEN);
> > > +#else
> > > +     return false;
> > > +#endif
> > > +}
> > > +
> > > +static inline bool is_direct_child_of_root_hub(struct usb_device *udev)
> > > +{
> > > +     return udev->parent == udev->bus->root_hub;
> > > +}
> > > +
> > >  static int btusb_mtk_setup(struct hci_dev *hdev)
> > >  {
> > >       struct btusb_data *data = hci_get_drvdata(hdev);
> > >       struct btmtk_data *btmtk_data = hci_get_priv(hdev);
> > > +     int err;
> > > 
> > >       /* MediaTek WMT vendor cmd requiring below USB resources to
> > >        * complete the handshake.
> > > @@ -2956,7 +2973,40 @@ static int btusb_mtk_setup(struct hci_dev *hdev)
> > >               btusb_mtk_claim_iso_intf(data);
> > >       }
> > > 
> > > -     return btmtk_usb_setup(hdev);
> > > +     err = btmtk_usb_setup(hdev);
> > > +     if (err)
> > > +             return err;
> > > +
> > > +     switch (btmtk_data->dev_id) {
> > > +     case 0x7922:
> > > +     case 0x7925:
> > > +             /*
> > > +              * All reports seen to be relevant to Ryzen-based laptops. These
> > > +              * NICs are usually used as OEM components thanks to some sort
> > > +              * of reference designs.
> > > +              *
> > > +              * Their popularity on other platforms is unclear. While there
> > > +              * is still a chance that the quirk may exist on other
> > > +              * platforms, be cautious and only apply the quirk to direct
> > > +              * children of Ryzen platforms's root hubs for the time being.
> > > +              *
> > > +              * In most cases the root hub is on the SoC or PCH, which needs
> > > +              * the quirk. Unfortunately, this can't distinguish root hubs on
> > > +              * PCIe add-in cards. Such roughness should be acceptable, as
> > > +              * PCIe USB controller add-in cards are less commonly used
> > > +              * nowadays. On the other hand, applying the quirk doesn't hurt
> > > +              * any functionalities either, as the device can still be used
> > > +              * as a wakeup source if desired.
> > > +              *
> > > +              * Theoretically, we could retrieve the root hub's PCI vendor ID
> > > +              * with some hierarchy magic, but that's too intrusive...
> > > +              */
> > > +             if (platform_is_ryzen() && is_direct_child_of_root_hub(data->udev))
> > > +                     set_bit(BTUSB_WAKEUP_BROKEN, &data->flags);
> > > +             break;
> > > +     }
> > > +
> > > +     return 0;
> > >  }
> > > 
> > >  static int btusb_mtk_shutdown(struct hci_dev *hdev)
> > > @@ -4532,11 +4582,26 @@ static int btusb_suspend(struct usb_interface *intf, pm_message_t message)
> > > 
> > >       BT_DBG("intf %p", intf);
> > > 
> > > -     /* Don't auto-suspend if there are connections or discovery in
> > > -      * progress; external suspend calls shall never fail.
> > > +     /*
> > > +      * It is reported that remote wakeup events could sometimes cause some
> > > +      * adapters completely unresponsive. Resetting the xHCI root hub doesn't
> > > +      * help at all, and recovering from such a state needs a power cycle.
> > > +      * Since disabling remote wakeup simply causes the USB core to gate
> > > +      * runtime autosuspend as well due to needs_remote_wakeup == 1, let's do
> > > +      * this ourselves to make our life easier. The interface can be safely
> > > +      * autosuspended as long as remote wakeup is disabled, i.e., after
> > > +      * closing the HCI device.
> > > +      *
> > > +      * Don't auto-suspend if there are connections or discovery in progress.
> > > +      *
> > > +      * External suspend calls shall never fail. Specifically, a device with
> > > +      * broken remote wakeup may still take the advantage of remote wakeup in
> > > +      * order to wake up the system from sleep if userspace has enabled it as
> > > +      * a wakeup source.
> > >        */
> > >       if (PMSG_IS_AUTO(message) &&
> > > -         (hci_conn_count(data->hdev) || hci_discovery_active(data->hdev)))
> > > +         ((test_bit(BTUSB_WAKEUP_BROKEN, &data->flags) && data->intf->needs_remote_wakeup) ||
> > > +          hci_conn_count(data->hdev) || hci_discovery_active(data->hdev)))
> > >               return -EBUSY;
> > > 
> > >       if (data->suspend_count++)
> > > 
> > > ---
> > > base-commit: dc59e4fea9d83f03bad6bddf3fa2e52491777482
> > > change-id: 230ba8c9-btmtk-ryzen-remote-wakeup-055a407682ef
> > > 
> > > Thanks,
> > > Rong
> 
>