mirror of
https://github.com/torvalds/linux.git
synced 2024-11-28 07:01:32 +00:00
951894cf30
External HDMI receivers have analog circuitry that needs to be powered-on when exiting standby, and a mechanism to detect PCM v. IEC61937 data. These two steps take time and up to 2-3 seconds of audio may be muted when starting playback. Intel hardware (Haswell and beyond) can keep the link active with a 'silent stream', so that the receiver does not go through those two steps when valid audio is transmitted. This mechanism relies on an setting the channel_id as 0xf, sending info packet and preventing the codec from going to D3, which will increase the platform static power consumption. The info packet assumes a basic 2ch stereo, and the silent stream is enabled when connecting a monitor. In case of format changes the detection of PCM v. IEC61937 needs to be re-run. In this case there is no way to avoid the 2-3s mute. The silent stream is enabled with a Kconfig option, as well as a kernel parameter should there be a need to override the build time default. This approach is used based on the power_save capability as an example, but in the future, it may be used with a kcontrol, depending on UCM support for HDaudio legacy. Signed-off-by: Harsha Priya <harshapriya.n@intel.com> Signed-off-by: Emmanuel Jillela <emmanuel.jillela@intel.com> Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com> Reported-by: kernel test robot <lkp@intel.com> Link: https://lore.kernel.org/r/1594068797-14011-1-git-send-email-harshapriya.n@intel.com Signed-off-by: Takashi Iwai <tiwai@suse.de> |
||
|---|---|---|
| .. | ||
| ac97 | ||
| aoa | ||
| arm | ||
| atmel | ||
| core | ||
| drivers | ||
| firewire | ||
| hda | ||
| i2c | ||
| isa | ||
| mips | ||
| oss | ||
| parisc | ||
| pci | ||
| pcmcia | ||
| ppc | ||
| sh | ||
| soc | ||
| sparc | ||
| spi | ||
| synth | ||
| usb | ||
| x86 | ||
| xen | ||
| ac97_bus.c | ||
| Kconfig | ||
| last.c | ||
| Makefile | ||
| sound_core.c | ||