Newer Intel chips (starting with Haswell) have advanced power management support, which needs support in both the i915 driver and the HDA driver for HDMI audio (and sometimes analog audio as well) to work correctly.
In addition, Canonical sometimes backports kernel drivers. This wiki page provides a short summary of that support.
Haswell / Intel Core 4th gen
- Power well: HDA controller
- Separate controllers/PCI devices for analog and HDMI audio
3.13
- Standard driver (i915)
Baytrail / Intel Atom Z36*, Z37*
- Power well: HDMI codec
- Same controller/PCI device for analog and HDMI audio
3.13
Standard driver (i915) on 3.13 < Ubuntu-3.13.0-45.74
Backported driver (i915_bdw) on 3.13 >= Ubuntu-3.13.0-45.74
3.16 and forward
Standard driver (i915)
Broadwell / Intel Core 5th gen
- Power well: HDA controller
- Separate PCI devices for analog and HDMI audio
3.13
- Backported driver (i915_bdw)
3.16 and forward
- Standard driver (i915)
Braswell / Intel N3*
- Power well: HDMI codec
- Same controller/PCI device for analog and HDMI audio
3.19
- Backported driver (i915_bpo)
Skylake
- Power well: HDMI codec
- Same controller/PCI device for analog and HDMI audio
3.19
- Backported driver (i915_bpo)