Messages in this thread | | | Date | Tue, 23 Aug 2022 13:46:36 +0200 | From | Takashi Iwai <> | Subject | Re: [REGRESSION 5.19.x] AMD HD-audio devices missing on 5.19 |
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On Tue, 23 Aug 2022 08:06:05 +0200, Takashi Iwai wrote: > > On Tue, 23 Aug 2022 03:00:21 +0200, > Jason Gunthorpe wrote: > > > > On Mon, Aug 22, 2022 at 04:12:59PM +0200, Takashi Iwai wrote: > > > Hi, > > > > > > we've received regression reports about the missing HD-audio devices > > > on AMD platforms, and this turned out to be caused by the commit > > > 512881eacfa72c2136b27b9934b7b27504a9efc2 > > > bus: platform,amba,fsl-mc,PCI: Add device DMA ownership management > > > > > > The details are found in openSUSE bugzilla: > > > https://bugzilla.suse.com/show_bug.cgi?id=1202492 > > > > > > The problem seems to be that HD-audio (both onboard analog and HDMI) > > > PCI devices are assigned to the same IOMMU group as AMD graphics PCI > > > device, and once after the AMDGPU is initialized beforehand, those > > > audio devices can't be probed since iommu_device_use_default_domain() > > > returns -EBUSY. > > > > Can you describe exactly what drivers are involved in this? If it is > > the above commit then several devices are sharing an iommu group and > > one of them (well, the only one already attached, I suppose) has made > > the group unsharable. > > > > With grep I don't see an obvious place where the AMDGPU driver would > > mess with the iommu configuration, so I have no guess. > > I have also no concrete clue, either :) > At least, drivers/gpu/drm/amd/amdkfd/kfd_iommu.c calls > amd_iommu_init_device(), and this invokes iommu_attach_group(), which > may change group->domain. But it was just my wild guess, and it might > be others, indeed. > > > It would be good to have some debugging to confirm if it is > > group->owner (should be impossible, suggests memory corruption if it > > is) or group->domain != group->default_domain. > > > > Most likely it is the later, but I can't see how that could happen on > > a system like this.. There is no obvious manipulation in AMDGPU, for > > instance. > > > > So debugging to find the backtrace for exactly when > > group->domain != group->default_domain > > Occurs for the troubled group would be necessary. > > OK, will try to build a test kernel with some debug prints and ask the > reporters. It may take some time.
It was tested now and confirmed that the call path is via AMDGPU, as expected: amdgpu_pci_probe -> amdgpu_driver_load_kms -> amdgpu_device_init -> amdgpu_amdkfd_device_init -> kgd2kfd_device_init -> kgd2kfd_resume_iommu -> kfd_iommu_resume -> amd_iommu_init_device -> iommu_attach_group -> __iommu_attach_group
At first AMDGPU driver is probed, and the iommu_attach_group() call above changes the assigned group->domain. Afterwards, when HD-audio devices are probed, it fails because: - Both HD-audio PCI devices belong to the very same IOMMU group as the AMD graphics PCI device - PCI core calls iommu_device_use_default_domain() and the check fails there because group->domain != group->default_domain
Takashi
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