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

["Chris Lu (陸稚泓)" <Chris.Lu@mediatek.com>]

Hi Rong,

Sorry for not getting back you sooner,
MediaTek BT team is currently looking for an AMD platform that can
reproduce this issue, but we haven't found a environment which has
similar problem.

About the patch, LGTM.
Your change can limit setting wakeup up capable to false to platform
with X86_FEATURE_ZEN. I also tried this patch locally with Arm-based
platform and it successfully avoids the issue of incorrectly disable BT
wakeup.

Thanks,
Chris Lu

On Thu, 2026-07-23 at 21:38 +0800, Rong Zhang wrote:
> 
> External email : Please do not click links or open attachments until
> you have verified the sender or the content.
> 
> 
> Hi Luiz, Chris,
> 
> Could you kindly take a look at the patch?
> 
> Thanks,
> Rong
> 
> 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>
> > ---
> > 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://urldefense.com/v3/__https://patch.msgid.link/20260629-btmtk-ryzen-remote-wakeup-v1-1-1d2f1cee6d22@rong.moe__;!!CTRNKA9wMg0ARbw!iS1xt56hol42azIYmHUZP_NI-N6WX6yn7_A1lf72MMvo1ZG_CNJRRSLgAbMx_AWK4kGyC2yBMQ$
> > ---
> >  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