Re: [alsa-devel] [PATCH] ASoC: Add support for BCM2708

On 05/22/2013 04:10 PM, Florian Meier wrote: [...]

diff --git a/sound/soc/bcm2708/bcm2708-i2s.c b/sound/soc/bcm2708/bcm2708-i2s.c new file mode 100644 index 0000000..a8e995f --- /dev/null +++ b/sound/soc/bcm2708/bcm2708-i2s.c @@ -0,0 +1,964 @@

[...]

+static int bcm2708_i2s_startup(struct snd_pcm_substream *substream,

• 	       struct snd_soc_dai *dai)
  

+{

• struct bcm2708_i2s_dev *dev = snd_soc_dai_get_drvdata(dai);
• if (!dev->first_stream) {

• dev->first_stream = substream;
  

• /* should this still be running stop it */
  

• bcm2708_i2s_stop_clock(dev);
  

• /* enable PCM block */
  

• bcm2708_i2s_set_bits(dev, BCM2708_I2S_CS_A_REG, BCM2708_I2S_EN);
  

• /*
  

•  * Disable STBY
  

•  * Requires at least 4 PCM clock cycles to take effect
  

•  */
  

• bcm2708_i2s_set_bits(dev, BCM2708_I2S_CS_A_REG,
  

• 		BCM2708_I2S_STBY);
  

• } else {

• struct snd_pcm_runtime *first_runtime =
  

• 	dev->first_stream->runtime;
  

• /*
  

•  * This is the second stream open, so we need to impose
  

•  * sample size and sampling rate constraints.
  

•  * This is because frame length and clock cannot be specified
  

•  * seperately.
  

•  *
  

•  * Note that this can cause a race condition if the
  

•  * second stream is opened before the first stream is
  

•  * fully initialized.  We provide some protection by
  

•  * checking to make sure the first stream is
  

•  * initialized, but it's not perfect.  ALSA sometimes
  

•  * re-initializes the driver with a different sample
  

•  * rate or size.  If the second stream is opened
  

•  * before the first stream has received its final
  

•  * parameters, then the second stream may be
  

•  * constrained to the wrong sample rate or size.
  

•  *
  

•  * We will continue in case of failure and recheck the
  

•  * constraint in hw_params.
  

•  */
  

• if (!first_runtime->format) {
  

• 	dev_err(substream->pcm->card->dev,
  

• 			"Set format in %s stream first! "
  

• 			"Initialization may fail.\n",
  

• 			substream->stream ==
  

• 			SNDRV_PCM_STREAM_PLAYBACK
  

• 			? "capture" : "playback");
  

• } else {
  

• 	snd_pcm_hw_constraint_minmax(substream->runtime,
  

• 			SNDRV_PCM_HW_PARAM_FORMAT,
  

• 			first_runtime->format,
  

• 			first_runtime->format);
  

• }
  

• if (!first_runtime->rate) {
  

• 	dev_err(substream->pcm->card->dev,
  

• 			"Set sampling rate in %s stream first! "
  

• 			"Initialization may fail!\n",
  

• 			substream->stream ==
  

• 			SNDRV_PCM_STREAM_PLAYBACK
  

• 			? "capture" : "playback");
  

• } else {
  

• 	snd_pcm_hw_constraint_minmax(substream->runtime,
  

• 			SNDRV_PCM_HW_PARAM_RATE,
  

• 			first_runtime->rate,
  

• 			first_runtime->rate);
  

• }
  

Setting the symmetric_rates lets the core take care of setting the proper constraints on the rate. It probably makes sense to also add a symmetric_formats since this isn't the only driver that has the requirement that the formats for playback and capture match.

• dev->second_stream = substream;
  

• }
• snd_soc_dai_set_dma_data(dai, substream,

• 	&dev->dma_params[substream->stream]);
  

• return 0;

+}

+static void bcm2708_i2s_shutdown(struct snd_pcm_substream *substream,

• struct snd_soc_dai *dai)
  

+{

• struct bcm2708_i2s_dev *dev = snd_soc_dai_get_drvdata(dai);
• bcm2708_i2s_stop(dev, substream);
• if (dev->first_stream == substream)

• dev->first_stream = dev->second_stream;
  

• dev->second_stream = NULL;
• /* If both streams are stopped, disable module and clock */
• if (!dev->first_stream) {

• /* Disable the module */
  

• bcm2708_i2s_clear_bits(dev, BCM2708_I2S_CS_A_REG,
  

• 		BCM2708_I2S_EN);
  

• /*
  

•  * Stopping clock is necessary, because stop does
  

•  * not stop the clock when SND_SOC_DAIFMT_CONT
  

•  */
  

• bcm2708_i2s_stop_clock(dev);
  

• }

+}

[...]

diff --git a/sound/soc/bcm2708/bcm2708-pcm.c b/sound/soc/bcm2708/bcm2708-pcm.c new file mode 100644 index 0000000..4b3e688 --- /dev/null +++ b/sound/soc/bcm2708/bcm2708-pcm.c @@ -0,0 +1,303 @@

I think you should be able to remove the bulk of this driver by using the generic PCM dmaengine driver.

[...]

+#include "bcm2708-pcm.h"

+static const struct snd_pcm_hardware bcm2708_pcm_hardware = {

• .info = SNDRV_PCM_INFO_MMAP |

• 		  SNDRV_PCM_INFO_MMAP_VALID |
  

• 		  SNDRV_PCM_INFO_INTERLEAVED |
  

• 		  SNDRV_PCM_INFO_PAUSE |
  

• 		  SNDRV_PCM_INFO_RESUME |
  

• 		  SNDRV_PCM_INFO_JOINT_DUPLEX |
  

• 		  SNDRV_PCM_INFO_NO_PERIOD_WAKEUP,
  

I don't think you actually support the last one, and neither pause and resume are supported.

• .formats = SNDRV_PCM_FMTBIT_S16_LE |

• 		  SNDRV_PCM_FMTBIT_S32_LE,
  

• .period_bytes_min = 32,
• .period_bytes_max = 64 * 1024,
• .periods_min = 2,
• .periods_max = 255,
• .buffer_bytes_max = 128 * 1024,

+};

[...]