From fb3df950833c1e8c39a82313942e6375f3f498c6 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Thu, 10 Nov 2016 22:25:28 +0100 Subject: ASoC: doc: ReSTize clocking.txt A simple conversion from a plain text file. Acked-by: Mark Brown Signed-off-by: Takashi Iwai --- Documentation/sound/alsa/soc/clocking.txt | 51 ------------------------------- Documentation/sound/soc/clocking.rst | 46 ++++++++++++++++++++++++++++ Documentation/sound/soc/index.rst | 1 + 3 files changed, 47 insertions(+), 51 deletions(-) delete mode 100644 Documentation/sound/alsa/soc/clocking.txt create mode 100644 Documentation/sound/soc/clocking.rst (limited to 'Documentation/sound') diff --git a/Documentation/sound/alsa/soc/clocking.txt b/Documentation/sound/alsa/soc/clocking.txt deleted file mode 100644 index b1300162e01c..000000000000 --- a/Documentation/sound/alsa/soc/clocking.txt +++ /dev/null @@ -1,51 +0,0 @@ -Audio Clocking -============== - -This text describes the audio clocking terms in ASoC and digital audio in -general. Note: Audio clocking can be complex! - - -Master Clock ------------- - -Every audio subsystem is driven by a master clock (sometimes referred to as MCLK -or SYSCLK). This audio master clock can be derived from a number of sources -(e.g. crystal, PLL, CPU clock) and is responsible for producing the correct -audio playback and capture sample rates. - -Some master clocks (e.g. PLLs and CPU based clocks) are configurable in that -their speed can be altered by software (depending on the system use and to save -power). Other master clocks are fixed at a set frequency (i.e. crystals). - - -DAI Clocks ----------- -The Digital Audio Interface is usually driven by a Bit Clock (often referred to -as BCLK). This clock is used to drive the digital audio data across the link -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 (LRC = Rate). - -Bit Clock can be generated as follows:- - -BCLK = MCLK / x - - or - -BCLK = LRC * x - - or - -BCLK = LRC * Channels * Word Size - -This relationship depends on the codec or SoC CPU in particular. In general -it is best to configure BCLK to the lowest possible speed (depending on your -rate, number of channels and word size) to save on power. - -It is also desirable to use the codec (if possible) to drive (or master) the -audio clocks as it usually gives more accurate sample rates than the CPU. - - - diff --git a/Documentation/sound/soc/clocking.rst b/Documentation/sound/soc/clocking.rst new file mode 100644 index 000000000000..32122d6877a3 --- /dev/null +++ b/Documentation/sound/soc/clocking.rst @@ -0,0 +1,46 @@ +============== +Audio Clocking +============== + +This text describes the audio clocking terms in ASoC and digital audio in +general. Note: Audio clocking can be complex! + + +Master Clock +------------ + +Every audio subsystem is driven by a master clock (sometimes referred to as MCLK +or SYSCLK). This audio master clock can be derived from a number of sources +(e.g. crystal, PLL, CPU clock) and is responsible for producing the correct +audio playback and capture sample rates. + +Some master clocks (e.g. PLLs and CPU based clocks) are configurable in that +their speed can be altered by software (depending on the system use and to save +power). Other master clocks are fixed at a set frequency (i.e. crystals). + + +DAI Clocks +---------- +The Digital Audio Interface is usually driven by a Bit Clock (often referred to +as BCLK). This clock is used to drive the digital audio data across the link +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 (LRC = Rate). + +Bit Clock can be generated as follows:- + +- BCLK = MCLK / x, or +- BCLK = LRC * x, or +- BCLK = LRC * Channels * Word Size + +This relationship depends on the codec or SoC CPU in particular. In general +it is best to configure BCLK to the lowest possible speed (depending on your +rate, number of channels and word size) to save on power. + +It is also desirable to use the codec (if possible) to drive (or master) the +audio clocks as it usually gives more accurate sample rates than the CPU. + + + diff --git a/Documentation/sound/soc/index.rst b/Documentation/sound/soc/index.rst index 4dd679927a91..0055abe16e7e 100644 --- a/Documentation/sound/soc/index.rst +++ b/Documentation/sound/soc/index.rst @@ -14,3 +14,4 @@ The documentation is spilt into the following sections:- platform machine pops-clicks + clocking -- cgit v1.2.3-59-g8ed1b