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ASoC: fsl_sai: Set SYNC bit of TCR2 to Asynchronous Mode
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There is one design rule according to SAI's reference manual:
If the transmitter bit clock and frame sync are to be used by both transmitter
and receiver, the transmitter must be configured for asynchronous operation
and the receiver for synchronous operation.

And SYNC of TCR2 is a 2-width control bit:
00 Asynchronous mode.
01 Synchronous with receiver.
10 Synchronous with another SAI transmitter.
11 Synchronous with another SAI receiver.

So the driver should have set SYNC bit of TCR2 to 0x0, and meanwhile set SYNC
bit of RCR2 to 0x1 (Synchronous with transmitter).

Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
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Nicolin Chen authored and Mark Brown committed Aug 16, 2014
1 parent ce7344a commit 855675f
Showing 1 changed file with 1 addition and 2 deletions.
3 changes: 1 addition & 2 deletions sound/soc/fsl/fsl_sai.c
Original file line number Diff line number Diff line change
Expand Up @@ -334,8 +334,7 @@ static int fsl_sai_trigger(struct snd_pcm_substream *substream, int cmd,
* Rx sync with Tx clocks: Clear SYNC for Tx, set it for Rx.
* Tx sync with Rx clocks: Clear SYNC for Rx, set it for Tx.
*/
regmap_update_bits(sai->regmap, FSL_SAI_TCR2, FSL_SAI_CR2_SYNC,
sai->synchronous[TX] ? FSL_SAI_CR2_SYNC : 0);
regmap_update_bits(sai->regmap, FSL_SAI_TCR2, FSL_SAI_CR2_SYNC, 0);
regmap_update_bits(sai->regmap, FSL_SAI_RCR2, FSL_SAI_CR2_SYNC,
sai->synchronous[RX] ? FSL_SAI_CR2_SYNC : 0);

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