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Date:   Mon, 22 Aug 2022 16:12:59 +0200
Message-ID: <874jy4cqok.wl-tiwai@suse.de>
From:   Takashi Iwai <tiwai@suse.de>
To:     Lu Baolu <baolu.lu@linux.intel.com>
Cc:     Joerg Roedel <jroedel@suse.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Jason Gunthorpe <jgg@nvidia.com>,
        Robin Murphy <robin.murphy@arm.com>,
        Eric Auger <eric.auger@redhat.com>,
        regressions@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: [REGRESSION 5.19.x] AMD HD-audio devices missing on 5.19
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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.

I'm not sure whether it's specific to PCI bus due to the assignment
logic of those IOMMU groups, or it's about the handling of the active
domain assignment.  In anyway, disabling IOMMU works around the
problem, and passing driver_managed_dma flag to the HD-audio driver
was also confirmed to work around it, too.

The problem persists with 6.0-rc1 kernel.

If you have / can give any fix patch or debug patch, let me know; I'll
build test kernels and ask the reporters.


thanks,

Takashi