On Thu, Oct 29, 2026 at 11:26 AM Mario Limonciello <[email protected]> wrote:
>
> On 10/29/26 10:14, Mike Lothian wrote:
> > On BOCO platforms the SBIOS can signal a display hotplug on a powered
> > off dGPU by notifying the dGPU's ACPI node. On the ASUS ROG Strix G513QY
> > the USB-C DP alt mode lanes are driven by the Navi 22, and the CPM
> > D3cold table handles the HPD GPE with only:
> >
> > Method (_L05) { Notify (\_SB.PCI0.GPP0.VGA, 0x81) }
> >
> > Nothing in Linux listens on that node: ATIF is bound to the iGPU and the
> > dGPU node is not an ACPI video bus. If the dGPU is in D3cold when a dock
> > is attached it stays off, no hotplug reaches userspace, the external
> > displays stay dark, and the level-triggered GPE keeps firing until the
> > dock is removed.
> >
> > Install an ACPI device notify handler on the dGPU's companion when BOCO
> > is used, and request a runtime resume on 0x81. Runtime resume already
> > re-detects all links and sends a hotplug event, so the new displays are
> > picked up; the device autosuspends again if nothing is enabled.
> >
> > Assisted-by: Claude:claude-opus-5-5
> > Signed-off-by: Mike Lothian <[email protected]>
> > ---
> > drivers/gpu/drm/amd/amdgpu/amdgpu.h | 1 +
> > drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c | 31 ++++++++++++++++++++++++
> > 2 files changed, 32 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> > index 7974f9b7944f..deb63122828d 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> > @@ -641,6 +641,7 @@ struct amdgpu_device {
> > bool need_swiotlb;
> > bool accel_working;
> > struct notifier_block acpi_nb;
> > + bool acpi_dgpu_notify;
> > struct notifier_block pm_nb;
> > struct amdgpu_i2c_chan *i2c_bus[AMDGPU_MAX_I2C_BUS];
> > struct debugfs_blob_wrapper debugfs_vbios_blob;
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
> > index 7f5abb03be1b..a4041f90b374 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
> > @@ -1280,6 +1280,23 @@ static int amdgpu_acpi_event(struct notifier_block
> > *nb,
> > return amdgpu_atif_handler(adev, entry);
> > }
> >
> > +/*
> > + * On BOCO platforms the SBIOS signals display hotplug on a powered-off
> > dGPU
>
> Although your system is a BOCO platform; I do think this same thing for
> this signaling to wakeup could apply to a BACO system too.
>
I would doubt it. In the BOCO case, the OEM has a mux on the HPD pins
and redirects them to the EC when the dGPU is powered off. For BACO,
in most cases that is just PCIe add in board so there is no way to
redirect the HPD pins.
@Mike Lothian does your system have ATIF? This is already code to
handle this. It sounds like it's just registering the wrong ACPI
node. You should be able to use the existing handler.
Alex
> > + * (e.g. USB-C DP alt mode HPD wired to the dGPU) with Notify(<dGPU>, 0x81)
> > + * on the dGPU's own ACPI node. Nothing else listens there, so wake the
> > + * device; runtime resume re-detects all links and sends a hotplug event.
> > + */
> > +static void amdgpu_acpi_dgpu_notify(acpi_handle handle, u32 event, void
> > *data)
> > +{
> > + struct amdgpu_device *adev = data;
> > +
> > + if (event != ACPI_VIDEO_NOTIFY_PROBE)
> > + return;
> > +
> > + dev_dbg(adev->dev, "ACPI notify 0x%x, requesting runtime resume\n",
> > event);
> > + pm_request_resume(adev->dev);
> > +}
> > +
> > /* Call all ACPI methods here */
> > /**
> > * amdgpu_acpi_init - init driver acpi support
> > @@ -1325,6 +1342,14 @@ int amdgpu_acpi_init(struct amdgpu_device *adev)
> > adev->acpi_nb.notifier_call = amdgpu_acpi_event;
> > register_acpi_notifier(&adev->acpi_nb);
> >
> > + if (!(adev->flags & AMD_IS_APU) && ACPI_COMPANION(adev->dev) &&
> > + adev->pm.rpm_mode == AMDGPU_RUNPM_BOCO)
>
> I'd install the notifier for BACO as well.
> > + adev->acpi_dgpu_notify =
> > +
> > !acpi_dev_install_notify_handler(ACPI_COMPANION(adev->dev),
> > + ACPI_DEVICE_NOTIFY,
> > +
> > amdgpu_acpi_dgpu_notify,
> > + adev);
> > +
> > return 0;
> > }
> >
> > @@ -1344,6 +1369,12 @@ void amdgpu_acpi_get_backlight_caps(struct
> > amdgpu_dm_backlight_caps *caps)
> > */
> > void amdgpu_acpi_fini(struct amdgpu_device *adev)
> > {
> > + if (adev->acpi_dgpu_notify) {
> > + acpi_dev_remove_notify_handler(ACPI_COMPANION(adev->dev),
> > + ACPI_DEVICE_NOTIFY,
> > + amdgpu_acpi_dgpu_notify);
> > + adev->acpi_dgpu_notify = false;
> > + }
> > unregister_acpi_notifier(&adev->acpi_nb);
> > }
> >
>
