On 03.06.2019 13:19, Willem Romkes wrote:
Hi,
We are using linux-at91 and lately I have been working on adding support for a custom soundcard, a dual tlv320aic3x codec on SAMA5D3 platform. This soundcard uses DSP A mode.
We are facing audio issues: When we playback a WAV file with a sine wave, the codec outputs far from a clean sine wave. The problem I think is that the CKI settings for the TMCR register isn't set correctly. see commit 20cf2603b122bf71fb54def1de6a2ad73d5ddb0b Author: Bo Shen voice.shen@atmel.com Date: Fri Jan 30 17:38:42 2015 +0800
ASoC: atmel_ssc_dai: fix the setting for DSP mode
When SCC work in DSP A mode, the data outputs/inputs are shift out on falling edge, the frame sync are sample on the rising edge.
Reported-by: Songjun Wu songjun.wu@atmel.com Signed-off-by: Bo Shen voice.shen@atmel.com Signed-off-by: Mark Brown broonie@kernel.org
diff --git a/sound/soc/atmel/atmel_ssc_dai.c b/sound/soc/atmel/atmel_ssc_dai.c index e691aab..35e44e4 100644 --- a/sound/soc/atmel/atmel_ssc_dai.c +++ b/sound/soc/atmel/atmel_ssc_dai.c @@ -502,7 +502,7 @@ static int atmel_ssc_hw_params(struct snd_pcm_substream *substream, rcmr = SSC_BF(RCMR_PERIOD, ssc_p->rcmr_period) | SSC_BF(RCMR_STTDLY, 1) | SSC_BF(RCMR_START, SSC_START_RISING_RF) - | SSC_BF(RCMR_CKI, SSC_CKI_RISING) + | SSC_BF(RCMR_CKI, SSC_CKI_FALLING) | SSC_BF(RCMR_CKO, SSC_CKO_NONE) | SSC_BF(RCMR_CKS, SSC_CKS_DIV);
@@ -517,7 +517,7 @@ static int atmel_ssc_hw_params(struct snd_pcm_substream *substream, tcmr = SSC_BF(TCMR_PERIOD, ssc_p->tcmr_period) | SSC_BF(TCMR_STTDLY, 1) | SSC_BF(TCMR_START, SSC_START_RISING_RF) - | SSC_BF(TCMR_CKI, SSC_CKI_RISING) + | SSC_BF(TCMR_CKI, SSC_CKI_FALLING) | SSC_BF(TCMR_CKO, SSC_CKO_CONTINUOUS) | SSC_BF(TCMR_CKS, SSC_CKS_DIV);
@@ -546,7 +546,7 @@ static int atmel_ssc_hw_params(struct snd_pcm_substream *substream, rcmr = SSC_BF(RCMR_PERIOD, 0) | SSC_BF(RCMR_STTDLY, START_DELAY) | SSC_BF(RCMR_START, SSC_START_RISING_RF) - | SSC_BF(RCMR_CKI, SSC_CKI_RISING) + | SSC_BF(RCMR_CKI, SSC_CKI_FALLING) | SSC_BF(RCMR_CKO, SSC_CKO_NONE) | SSC_BF(RCMR_CKS, ssc->clk_from_rk_pin ? SSC_CKS_PIN : SSC_CKS_CLOCK);
For both the TCMR and RCMR the CKI is set to SSC_CKI_FALLING, but I think for the TCMR the CKI should be set to SSC_CKI_RISING. See datasheet:
TCMR CKI: "1: The data outputs (Data and Frame Sync signals) are shifted out on Transmit Clock rising edge. The Frame sync signal input is sampled on Transmit clock falling edge."
RCMR CKI: "0: The data inputs (Data and Frame Sync signals) are sampled on Receive Clock falling edge. The Frame Sync signal out- put is shifted out on Receive Clock rising edge."
Setting the CKI in TCMR to SSC_CKI_RISING to fixes our issues.
Hi Willem,
It this DS of the codec you are using? http://www.ti.com/lit/ds/symlink/tlv320aic33.pdf
Are you using the DSP mode described in figure 25 DSP Serial Bus Mode Operation? If yes, then you should use the DSP_B mode...
Thanks and best regards, Codrin