[3/3] ASoC: DaVinci: More accurate calculation for clock divider for McBSP (I2S)

Commit Message

Raffaele Recalcati July 2, 2010, 5:12 p.m. UTC

None

Patch

diff --git a/arch/arm/mach-davinci/include/mach/asp.h b/arch/arm/mach-davinci/include/mach/asp.h
index 0847d21..21c886e 100644
--- a/arch/arm/mach-davinci/include/mach/asp.h
+++ b/arch/arm/mach-davinci/include/mach/asp.h
@@ -73,6 +73,13 @@  struct snd_platform_data {
 	 */
 	int clk_input_pin;
 
+	/*
+	 * This define works when both clock and FS are output for the cpu
+	 * and makes clock more accurate (FS is not symmetrical and the
+	 * clock is very fast.
+	 */
+	bool i2s_accurate_clock;
+
 	/* McASP specific fields */
 	int tdm_slots;
 	u8 op_mode;
diff --git a/sound/soc/davinci/davinci-i2s.c b/sound/soc/davinci/davinci-i2s.c
index 17f594f..2fb1209 100644
--- a/sound/soc/davinci/davinci-i2s.c
+++ b/sound/soc/davinci/davinci-i2s.c
@@ -154,6 +154,7 @@  struct davinci_mcbsp_dev {
 	unsigned int fmt;
 	int clk_div;
 	int clk_input_pin;
+	bool i2s_accurate_clock;
 };
 
 static inline void davinci_mcbsp_write_reg(struct davinci_mcbsp_dev *dev,
@@ -447,6 +448,24 @@  static int davinci_i2s_hw_params(struct snd_pcm_substream *substream,
 		       DAVINCI_MCBSP_SRGR_CLKSM;
 		srgr |= DAVINCI_MCBSP_SRGR_FWID(mcbsp_word_length *
 						8 - 1);
+		if (dev->i2s_accurate_clock) {
+			clk_div = 256;
+			do {
+				framesize = (freq / (--clk_div)) /
+				params->rate_num *
+					params->rate_den;
+			} while (((framesize < 33) || (framesize > 4095)) &&
+				 (clk_div));
+			clk_div--;
+			srgr |= DAVINCI_MCBSP_SRGR_FPER(framesize - 1);
+		} else {
+			/* symmetric waveforms */
+			clk_div = freq / (mcbsp_word_length * 16) /
+				  params->rate_num * params->rate_den;
+			srgr |= DAVINCI_MCBSP_SRGR_FPER(mcbsp_word_length *
+							16 - 1);
+		}
+
 		/* symmetric waveforms */
 		clk_div = freq / (mcbsp_word_length * 16) /
 			  params->rate_num * params->rate_den;
@@ -662,6 +681,7 @@  static int davinci_i2s_probe(struct platform_device *pdev)
 		dev->dma_params[SNDRV_PCM_STREAM_CAPTURE].sram_size =
 			pdata->sram_size_capture;
 		dev->clk_input_pin = pdata->clk_input_pin;
+		dev->i2s_accurate_clock = pdata->i2s_accurate_clock;
 	}
 	dev->clk = clk_get(&pdev->dev, NULL);
 	if (IS_ERR(dev->clk)) {