Re: [REGRESSION] AMDISP failure with kernel v7.0-rc2 due to Commit: 02c057ddefef5

[Rafael J. Wysocki]

On Fri, Mar 6, 2026 at 1:45 PM Mario Limonciello <superm1@xxxxxxxxxx> wrote:
>
>
>
> On 3/6/26 6:01 AM, Rafael J. Wysocki wrote:
> > On Fri, Mar 6, 2026 at 1:35 AM Mario Limonciello (AMD) (kernel.org)
> > <superm1@xxxxxxxxxx> wrote:
> >>
> >>
> >>
> >> On 3/5/2026 5:11 PM, Nirujogi, Pratap wrote:
> >>> Hi Rafael,
> >>>
> >>> In kernel version 7.0-rc2, the AMDISP device reports the following
> >>> errors when created via mfd_add_hotplug_devices.
> >>>
> >>> [    5.236645] ACPI: video: Video Device [GFX0] (multi-head: yes  rom:
> >>> no  post: no)
> >>> [    5.236744] input: Video Bus as /devices/
> >>> pci0000:00/0000:00:08.1/0000:c3:00.0/amd_isp_capture.1.auto/input/input21
> >>> [    5.236779] acpi device:14: Error installing notify handler
> >>> [    5.236782] acpi device:15: Error installing notify handler
> >>> [    5.236783] acpi device:16: Error installing notify handler
> >>> [    5.236784] acpi device:17: Error installing notify handler
> >>> [    5.236785] acpi device:18: Error installing notify handler
> >>> [    5.236786] acpi device:19: Error installing notify handler
> >>> [    5.236786] acpi device:1a: Error installing notify handler
> >>> [    5.236787] acpi device:1b: Error installing notify handler
> >>> [    5.236788] acpi device:1c: Error installing notify handler
> >>>
> >>> These failures indicate AMDISP device is incorrectly detected as ACPI
> >>> Video device while it is not.
> >>>
> >>> The seems like a regression caused by the change that converts the ACPI
> >>> video device to a platform device (commit: 02c057ddefef5).
> >>>
> >>> Issue is not observed in 6.19-rc6, and also when this change is reverted
> >>> in 7.0-rc2.
> >>>
> >>> I really appreciate your inputs on addressing this issue and helping us
> >>> make progress on 7.0 rc2.
> >>>
> >>> Steps followed to reproduce the issue:
> >>>
> >>> 1. Apply AMDISP v9 patch series [1] on top of kernel v7.0-rc2
> >>> 2. Add NULL check for “dev->type” in isp_genpd_add_device() [2] (to
> >>> avoid kernel panic found in v7.0-rc2)
> >>> 3. Build kernel with:
> >>>       - CONFIG_AMD_ISP_PLATFORM=y
> >>>       - CONFIG_VIDEO_AMD_ISP4_CAPTURE=m
> >>> 4. Install kernel on AMDISP supported system (HP ZBook Ultra G1a)
> >>> 5. Boot system to see the failures
> >>>
> >>> [1] https://lore.kernel.org/all/20260302073020.148277-1-Bin.Du@xxxxxxx/
> >>> [2] https://github.com/torvalds/linux/blob/master/drivers/gpu/drm/amd/
> >>> amdgpu/isp_v4_1_1.c#L132
> >>>
> >>> Thanks,
> >>> Pratap
> >>>
> >>>
> >>>
> >>
> >> It's a bit weird to see it even probe in this path in the first place.
> >> acpi_video_bus_probe() getting called with the mfd device doesn't seem
> >> right to me.
> >>
> >> I wonder if it's because ISP is an MFD device of GPU (and thus LNXVIDEO
> >> ends up matching).
> >>
> >> Would a sensible solution be to reject mfd device types in
> >> acpi_video_bus_probe()?
> >
> > Every platform device with LNXVIDEO in the device ID list will be
> > matched and so probed.
> >
> > I'm wondering how those devices get that ID though.
>
> Yeah me too.  I was surprised an MFD device got it.
>
> Pratap - can you figure this out before we go too far in this path?
>
> If they really shouldn't have LNXVIDEO fixing that may be a better solution.

The current theory is that they share the ACPI companion with the
"right" ACPI video bus device.  If that is confirmed (for example, by
testing the patch posted by me earlier), I will be wondering why they
do so.

If the ACPI companion sharing is necessary for some reason, maybe
changing the type of the other devices to something like auxiliary
devices can be considered.

> >
> > Also, is this really a mainline regression?  AMDISP patches are not in
> > the mainline, no?
>
> The amdgpu half of it is mainline, the other half is still on the lists.

Well, I mean the other part seems to be necessary to reproduce the error.

Also please note that this error is just a bit noisy, but it actually
means that the probe has failed which is what we want.