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| author | Mengdong Lin <mengdong.lin@intel.com> | 2014-06-26 12:45:16 +0200 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2014-06-26 15:47:42 +0200 |
| commit | a07187c992be945ab561b370cbb49cfd72064c3c (patch) | |
| tree | 2db9f7483d06befd0b159f3b08450eba06e712ab /Documentation | |
| parent | ALSA: usb-audio: Fix races at disconnection and PCM closing (diff) | |
| download | linux-a07187c992be945ab561b370cbb49cfd72064c3c.tar.xz linux-a07187c992be945ab561b370cbb49cfd72064c3c.zip | |
ALSA: hda - restore BCLK M/N values when resuming HSW/BDW display controller
For Intel Haswell/Broadwell display HD-A controller, the 24MHz HD-A link BCLK
is converted from Core Display Clock (CDCLK): BCLK = CDCLK * M / N
And there are two registers EM4 and EM5 to program M, N value respectively.
The EM4/EM5 values will be lost and when the display power well is disabled.
BIOS programs CDCLK selected by OEM and EM4/EM5, but BIOS has no idea about
display power well on/off at runtime. So the M/N can be wrong if non-default
CDCLK is used when the audio controller resumes, which results in an invalid
BCLK and abnormal audio playback rate. So this patch saves and restores valid
M/N values on controller suspend/resume.
And 'struct hda_intel' is defined to contain standard HD-A 'struct azx' and
Intel specific fields, as Takashi suggested.
Signed-off-by: Mengdong Lin <mengdong.lin@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'Documentation')
0 files changed, 0 insertions, 0 deletions