Created attachment 108511 [details]
Various system information

[1.] One line summary of the problem: 
Intel HDMI Audio not working with IOMMU enabled

[2.] Full description of the problem/report: 
On an Intel Haswell platform (ASUS Sabertooth Z87 + Intel i7 4770), no sound can be heard from the HDMI output of the integrated GPU if the IOMMU is enabled with the boot parameter inteL_iommu=on. The HDMI output is detected correctly and everything seems to be in order, except that there is not sound coming out of the boxes. Without intel_iommu=on, sound is working as expected. The system also contains an ATI GPU which is NOT used, all ATI drivers are blacklisted.

[3.] Keywords (i.e., modules, networking, kernel):
sound, iommu, haswell

[4.] Kernel version (from /proc/version): 
Linux version 3.11.0-031100-generic (apw@gomeisa) (gcc version 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5) ) #201309021735 SMP Mon Sep 2 21:36:21 UTC 2013

[5.] Output of Oops.. message (if applicable) 
-

[6.] A small shell script or example program which triggers the problem (if possible) 
-

[7.] Environment 
Description:	Ubuntu Saucy Salamander (development branch)
Release:	13.10

[7.1.] Software
See Attachment software

[7.2.] Processor information (from /proc/cpuinfo): 
See attachment cpuinfo

[7.3.] Module information (from /proc/modules): 
See attachment modules

[7.4.] Loaded driver and hardware information (/proc/ioports, /proc/iomem) 
See attachment drivers

[7.5.] PCI information ('lspci -vvv' as root) 
See attachment lspci

[7.6.] SCSI information (from /proc/scsi/scsi) 
Attached devices:
Host: scsi0 Channel: 00 Id: 00 Lun: 00
  Vendor: ATA      Model: SAMSUNG SSD 830  Rev: CXM0
  Type:   Direct-Access                    ANSI  SCSI revision: 05
Host: scsi1 Channel: 00 Id: 00 Lun: 00
  Vendor: ATA      Model: WDC WD30EFRX-68A Rev: 80.0
  Type:   Direct-Access                    ANSI  SCSI revision: 05
Host: scsi3 Channel: 00 Id: 00 Lun: 00
  Vendor: HL-DT-ST Model: BD-RE  BH16NS40  Rev: 1.00
  Type:   CD-ROM                           ANSI  SCSI revision: 05

[7.7.] Other information that might be relevant to the problem (please look in /proc and include all information that you think to be relevant): 
ls /proc: 
1     1216  17    2170  2297  2614  2749  2857  2987  3342  4078  44    57   72         consoles     kpagecount     stat
10    1217  170   2174  2298  2623  2750  2859  299   34    41    4484  572  73         cpuinfo      kpageflags     swaps
108   1231  171   2175  2299  2624  2753  2860  2996  3433  4103  45    573  732        crypto       latency_stats  sys
109   1251  172   2176  23    2625  2754  2862  3     3435  4135  46    574  736        devices      loadavg        sysrq-trigger
11    1259  173   2189  2303  2630  2758  2863  30    3439  4154  465   58   737        diskstats    locks          sysvipc
110   1268  18    22    231   2631  2761  2864  300   3451  4162  47    59   74         dma          mdstat         timer_list
111   13    187   2206  2320  2634  2771  2870  3004  3455  4172  479   6    789        dri          meminfo        timer_stats
1114  1323  19    2228  233   2636  2795  2882  3010  35    4174  4790  60   8          driver       misc           tty
1115  1359  198   2229  24    2640  28    2893  3070  36    42    4797  61   85         execdomains  modules        uptime
1116  1383  1985  2246  2410  2651  280   29    3075  3689  4210  49    610  855        fb           mounts         version
1117  1385  2     228   2492  2656  2817  2910  3079  37    4228  5     62   88         filesystems  mtrr           vmallocinfo
1118  14    20    2286  25    2670  282   2914  3080  3767  428   50    63   884        fs           net            vmstat
1134  1449  204   2287  2503  27    2824  2918  31    38    4280  51    64   89         interrupts   pagetypeinfo   zoneinfo
1135  1457  2095  2288  2520  2703  283   2936  32    3882  4295  53    65   9          iomem        partitions
1137  15    21    2291  2568  2708  284   2956  320   3897  43    54    66   acpi       ioports      sched_debug
1138  1564  2103  2292  2569  2726  2845  296   321   39    4308  544   68   asound     irq          schedstat
1175  16    2122  2293  2583  2729  285   2962  322   3958  4342  549   69   buddyinfo  kallsyms     scsi
1176  166   2124  2294  2584  2742  2850  2966  3229  40    4392  55    7    bus        kcore        self
1177  167   2128  2295  2589  2746  2854  297   323   4065  4398  550   70   cgroups    key-users    slabinfo
12    169   2131  2296  26    2748  2855  2972  33    4070  4399  56    71   cmdline    kmsg         softirqs

[X.] Other notes, patches, fixes, workarounds: 
Bug initially reported on Launchpad:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1223840