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Diffstat (limited to 'Documentation/sound/alsa/soc/clocking.txt')
| -rw-r--r-- | Documentation/sound/alsa/soc/clocking.txt | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/Documentation/sound/alsa/soc/clocking.txt b/Documentation/sound/alsa/soc/clocking.txt index 88a16c9e1979..1f55fd8cb117 100644 --- a/Documentation/sound/alsa/soc/clocking.txt +++ b/Documentation/sound/alsa/soc/clocking.txt @@ -26,9 +26,9 @@ between the codec and CPU. The DAI also has a frame clock to signal the start of each audio frame. This clock is sometimes referred to as LRC (left right clock) or FRAME. This clock -runs at exactly the sample rate. +runs at exactly the sample rate (LRC = Rate). -Bit Clock is usually always a ratio of MCLK or a multiple of LRC. i.e. +Bit Clock can be generated as follows:- BCLK = MCLK / x @@ -36,9 +36,14 @@ BCLK = MCLK / x BCLK = LRC * x + or + +BCLK = LRC * Channels * Word Size + This relationship depends on the codec or SoC CPU in particular. ASoC can quite -easily match a codec that generates BCLK by division (FSBD) with a CPU that -generates BCLK by multiplication (FSB). +easily match BCLK generated by division (SND_SOC_DAI_BFS_DIV) with BCLK by +multiplication (SND_SOC_DAI_BFS_RATE) or BCLK generated by +Rate * Channels * Word size (RCW or SND_SOC_DAI_BFS_RCW). ASoC Clocking |