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| author | Troy Kisky <troy.kisky@boundarydevices.com> | 2008-12-18 12:36:41 -0700 |
|---|---|---|
| committer | Mark Brown <broonie@opensource.wolfsonmicro.com> | 2008-12-20 13:05:38 +0000 |
| commit | 664b4af859d43714fd2a90aa434e454355659d0e (patch) | |
| tree | 4e04057e30d991f2d16ed771548ab91a2c34b9c1 /sound | |
| parent | 1152a1959f8440db9536f6df758274443f9b5b37 (diff) | |
| download | lwn-664b4af859d43714fd2a90aa434e454355659d0e.tar.gz lwn-664b4af859d43714fd2a90aa434e454355659d0e.zip | |
ALSA: ASoC: DaVinci: davinci-i2s add comments to explain polarity
Document the current polarity choices.
Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Diffstat (limited to 'sound')
| -rw-r--r-- | sound/soc/davinci/davinci-i2s.c | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/sound/soc/davinci/davinci-i2s.c b/sound/soc/davinci/davinci-i2s.c index 81ff5c37ab56..156e3e95d914 100644 --- a/sound/soc/davinci/davinci-i2s.c +++ b/sound/soc/davinci/davinci-i2s.c @@ -235,18 +235,45 @@ static int davinci_i2s_set_dai_fmt(struct snd_soc_dai *cpu_dai, switch (fmt & SND_SOC_DAIFMT_INV_MASK) { case SND_SOC_DAIFMT_IB_NF: + /* CLKRP Receive clock polarity, + * 1 - sampled on rising edge of CLKR + * valid on rising edge + * CLKXP Transmit clock polarity, + * 1 - clocked on falling edge of CLKX + * valid on rising edge + * FSRP Receive frame sync pol, 0 - active high + * FSXP Transmit frame sync pol, 0 - active high + */ w = davinci_mcbsp_read_reg(dev, DAVINCI_MCBSP_PCR_REG); MOD_REG_BIT(w, DAVINCI_MCBSP_PCR_CLKXP | DAVINCI_MCBSP_PCR_CLKRP, 1); davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_PCR_REG, w); break; case SND_SOC_DAIFMT_NB_IF: + /* CLKRP Receive clock polarity, + * 0 - sampled on falling edge of CLKR + * valid on falling edge + * CLKXP Transmit clock polarity, + * 0 - clocked on rising edge of CLKX + * valid on falling edge + * FSRP Receive frame sync pol, 1 - active low + * FSXP Transmit frame sync pol, 1 - active low + */ w = davinci_mcbsp_read_reg(dev, DAVINCI_MCBSP_PCR_REG); MOD_REG_BIT(w, DAVINCI_MCBSP_PCR_FSXP | DAVINCI_MCBSP_PCR_FSRP, 1); davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_PCR_REG, w); break; case SND_SOC_DAIFMT_IB_IF: + /* CLKRP Receive clock polarity, + * 1 - sampled on rising edge of CLKR + * valid on rising edge + * CLKXP Transmit clock polarity, + * 1 - clocked on falling edge of CLKX + * valid on rising edge + * FSRP Receive frame sync pol, 1 - active low + * FSXP Transmit frame sync pol, 1 - active low + */ w = davinci_mcbsp_read_reg(dev, DAVINCI_MCBSP_PCR_REG); MOD_REG_BIT(w, DAVINCI_MCBSP_PCR_CLKXP | DAVINCI_MCBSP_PCR_CLKRP | @@ -255,6 +282,15 @@ static int davinci_i2s_set_dai_fmt(struct snd_soc_dai *cpu_dai, davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_PCR_REG, w); break; case SND_SOC_DAIFMT_NB_NF: + /* CLKRP Receive clock polarity, + * 0 - sampled on falling edge of CLKR + * valid on falling edge + * CLKXP Transmit clock polarity, + * 0 - clocked on rising edge of CLKX + * valid on falling edge + * FSRP Receive frame sync pol, 0 - active high + * FSXP Transmit frame sync pol, 0 - active high + */ break; default: return -EINVAL; |