Comment 0 for bug 1223840

I am using Ubuntu Saucy Development Branch and I noticed that the HDMI audio output of the intel graphics stops working if the IOMMU is enabled with the kernel boot parameter intel_iommu=on. I need the IOMMU to pass an ATI graphics card to a qemu virtual machine.

My hardware consists of an ASUS Sabertooth Z87 mainboard with an Intel i7 4770 cpu (Haswell).

The HDMI output is detected and displayed correctly but no sound can be heard. If the IOMMU is disabled, everything works fine.

ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: linux-image-3.11.0-7-generic 3.11.0-7.13
ProcVersionSignature: Ubuntu 3.11.0-7.13-generic 3.11.0
Uname: Linux 3.11.0-7-generic x86_64
ApportVersion: 2.12.1-0ubuntu3
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC1: htpc 2602 F.... pulseaudio
 /dev/snd/controlC0: htpc 2602 F.... pulseaudio
Date: Wed Sep 11 14:00:38 2013
InstallationDate: Installed on 2013-07-19 (54 days ago)
InstallationMedia: Ubuntu 13.04 "Raring Ringtail" - Release amd64 (20130424)
IwConfig:
 br0 no wireless extensions.

 eth2 no wireless extensions.

 lo no wireless extensions.
MachineType: ASUS All Series
MarkForUpload: True
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.11.0-7-generic root=/dev/mapper/local_system-linux ro quiet splash intel_iommu=on pcie_acs_override=downstream vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-3.11.0-7-generic N/A
 linux-backports-modules-3.11.0-7-generic N/A
 linux-firmware 1.113
RfKill:

SourcePackage: linux
UpgradeStatus: Upgraded to saucy on 2013-07-22 (50 days ago)
dmi.bios.date: 08/19/2013
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 1405
dmi.board.asset.tag: To be filled by O.E.M.
dmi.board.name: SABERTOOTH Z87
dmi.board.vendor: ASUSTeK COMPUTER INC.
dmi.board.version: Rev 1.xx
dmi.chassis.asset.tag: Asset-1234567890
dmi.chassis.type: 3
dmi.chassis.vendor: Chassis Manufacture
dmi.chassis.version: Chassis Version
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr1405:bd08/19/2013:svnASUS:pnAllSeries:pvrSystemVersion:rvnASUSTeKCOMPUTERINC.:rnSABERTOOTHZ87:rvrRev1.xx:cvnChassisManufacture:ct3:cvrChassisVersion:
dmi.product.name: All Series
dmi.product.version: System Version
dmi.sys.vendor: ASUS