Re: [PATCH] asoc tlv320aic33: skip usage of PLL in some cases

[Daniel Mack <daniel@caiaq.org>]

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On Fri, Apr 18, 2008 at 11:58:49AM +0300, Jarkko Nikula wrote:
> > No, the 256-clock mode is for output only, while in my setup the TLV is
> > in slave mode. I attached this chip to the I2S output of an PXA270 which
> > always outputs sample rate * 256 as system clock. In this very case, the
> > PLL can be bypassed by selecting the left path described on page 27.
> >
> 
> Ok, now I see. Probably you should refer it as, at least in comment, 128*Q
> instead of 256 eventhough the driver is not currently touching the Q value
> in AIC3X_PLL_PROGA_REG.

Well, the constraint for that condition is that MCLK = 256*WCLK, and the
reason why that works for the chip without PLL is that Q=2. I stated
that a little better in the attached patch.

> > AIC3X_SAMPLE_RATE_SEL_REG defaults to 0 which is what I want in this
> > case. Thus, I don't have to write it.
> >
> >
> Are you sure this is a general case?

Well, the reset default is 0 (as stated on page 44) and set_hw_params()
is the only location where this value is written. So if it's never 
written with a different value, it should always be set to its default,
no?

Daniel


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diff --git a/sound/soc/codecs/tlv320aic3x.c b/sound/soc/codecs/tlv320aic3x.c
index 630684f..0f0bda2 100644
--- a/sound/soc/codecs/tlv320aic3x.c
+++ b/sound/soc/codecs/tlv320aic3x.c
@@ -720,7 +720,7 @@ static inline int aic3x_get_divs(int mclk, int rate)
 			return i;
 	}
 
-	return 0;
+	return -1;
 }
 
 static int aic3x_hw_params(struct snd_pcm_substream *substream,
@@ -730,11 +730,42 @@ static int aic3x_hw_params(struct snd_pcm_substream *substream,
 	struct snd_soc_device *socdev = rtd->socdev;
 	struct snd_soc_codec *codec = socdev->codec;
 	struct aic3x_priv *aic3x = codec->private_data;
-	int i;
+	int i, skip_pll;
 	u8 data, pll_p, pll_r, pll_j;
 	u16 pll_d;
 
-	i = aic3x_get_divs(aic3x->sysclk, params_rate(params));
+	/* select data word length */
+	data =
+	    aic3x_read_reg_cache(codec, AIC3X_ASD_INTF_CTRLB) & (~(0x3 << 4));
+	switch (params_format(params)) {
+	case SNDRV_PCM_FORMAT_S16_LE:
+		break;
+	case SNDRV_PCM_FORMAT_S20_3LE:
+		data |= (0x01 << 4);
+		break;
+	case SNDRV_PCM_FORMAT_S24_LE:
+		data |= (0x02 << 4);
+		break;
+	case SNDRV_PCM_FORMAT_S32_LE:
+		data |= (0x03 << 4);
+		break;
+	}
+	aic3x_write(codec, AIC3X_ASD_INTF_CTRLB, data);
+
+	/* Do not use the PLL in case our MCLK is 256 * sample rate.
+	 * The Q value defaults to 2 so the codec sees MCLK as clock
+	 * input (refer to datasheet page 27).
+	 * In this case, use a fake entry in the dividers table to get
+	 * the reference freq */
+	skip_pll = (aic3x->sysclk == params_rate(params) * 256);
+
+	if (skip_pll)
+		i = aic3x_get_divs(aic3x_divs[0].mclk, params_rate(params));
+	else
+		i = aic3x_get_divs(aic3x->sysclk, params_rate(params));
+
+	if (i < 0)
+		return -EINVAL;
 
 	/* Route Left DAC to left channel input and
 	 * right DAC to right channel input */
@@ -755,6 +786,9 @@ static int aic3x_hw_params(struct snd_pcm_substream *substream,
 	}
 	aic3x_write(codec, AIC3X_CODEC_DATAPATH_REG, data);
 
+	if (skip_pll)
+		return 0;
+
 	/* codec sample rate select */
 	data = aic3x_divs[i].sr_reg;
 	data |= (data << 4);
@@ -782,24 +816,6 @@ static int aic3x_hw_params(struct snd_pcm_substream *substream,
 	aic3x_write(codec, AIC3X_PLL_PROGD_REG,
 		    (pll_d & 0x3F) << PLLD_LSB_SHIFT);
 
-	/* select data word length */
-	data =
-	    aic3x_read_reg_cache(codec, AIC3X_ASD_INTF_CTRLB) & (~(0x3 << 4));
-	switch (params_format(params)) {
-	case SNDRV_PCM_FORMAT_S16_LE:
-		break;
-	case SNDRV_PCM_FORMAT_S20_3LE:
-		data |= (0x01 << 4);
-		break;
-	case SNDRV_PCM_FORMAT_S24_LE:
-		data |= (0x02 << 4);
-		break;
-	case SNDRV_PCM_FORMAT_S32_LE:
-		data |= (0x03 << 4);
-		break;
-	}
-	aic3x_write(codec, AIC3X_ASD_INTF_CTRLB, data);
-
 	return 0;
 }
 
@@ -826,16 +842,8 @@ static int aic3x_set_dai_sysclk(struct snd_soc_codec_dai *codec_dai,
 	struct snd_soc_codec *codec = codec_dai->codec;
 	struct aic3x_priv *aic3x = codec->private_data;
 
-	switch (freq) {
-	case 12000000:
-	case 19200000:
-	case 22579200:
-	case 33868800:
-		aic3x->sysclk = freq;
-		return 0;
-	}
-
-	return -EINVAL;
+	aic3x->sysclk = freq;
+	return 0;
 }
 
 static int aic3x_set_dai_fmt(struct snd_soc_codec_dai *codec_dai,

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