mirror of https://gitee.com/openkylin/linux.git
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> |
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| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
README
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.