On Mon, Feb 13, 2017 at 10:27:15AM +1100, Matt Flax wrote:
This patch adds multitrack capability if in DSP mode A and the codec is master.
In bcm2835_i2s_startup, snd_pcm_hw_constraint_minmax is used to set max channels to 8 if both SND_SOC_DAIFMT_CBM_CFM and SND_SOC_DAIFMT_DSP_A are set. Otherwise, max channels is set to 2. Min channels is always set to 2. These settings are accomplished using the SNDRV_PCM_HW_PARAM_CHANNELS variable.
In bcm2835_i2s_shutdown max channels is set to 2 by default.
In bcm2835_i2s_hw_params, DSP mode A format is now an option. Before replicating the format variable (from ch2 to ch1) for register loading, requested channels are checked to be either 2 or 8. This can be expaneded later to accomodate other channel counts if supported by the sound card hardware.
Signed-off-by: Matt Flax flatmax@flatmax.org
<snip>
@@ -312,6 +313,7 @@ static int bcm2835_i2s_hw_params(struct snd_pcm_substream *substream,
switch (params_channels(params)) { case 2:
- case 8: format = BCM2835_I2S_CH1(format) | BCM2835_I2S_CH2(format); format |= BCM2835_I2S_CH1(BCM2835_I2S_CHPOS(ch1pos)); format |= BCM2835_I2S_CH2(BCM2835_I2S_CHPOS(ch2pos));
@@ -526,7 +528,16 @@ static int bcm2835_i2s_startup(struct snd_pcm_substream *substream, regmap_update_bits(dev->i2s_regmap, BCM2835_I2S_CS_A_REG, BCM2835_I2S_STBY, BCM2835_I2S_STBY);
- return 0;
- /* Set the max channels to 8 if the codec is master and
* we are in DSP A mode. Otherwise only allow 2 channels.*/- if (dev->fmt &
(SND_SOC_DAIFMT_CBM_CFM | SND_SOC_DAIFMT_DSP_A))return snd_pcm_hw_constraint_minmax(substream->runtime,SNDRV_PCM_HW_PARAM_CHANNELS, 2, 8);
Would it be worth using snd_pcm_hw_constraint_list here? We are going to error out of hw_params if the user requests anything other than 2 or 8 channels so we should probably just constrain to those two.
- else
return snd_pcm_hw_constraint_minmax(substream->runtime,SNDRV_PCM_HW_PARAM_CHANNELS, 2, 2);
snd_pcm_hw_constraint_single, it's exactly the same thing but I guess we should probably use the helper if it exists.
}
static void bcm2835_i2s_shutdown(struct snd_pcm_substream *substream, @@ -549,6 +560,10 @@ static void bcm2835_i2s_shutdown(struct snd_pcm_substream *substream, * not stop the clock when SND_SOC_DAIFMT_CONT */ bcm2835_i2s_stop_clock(dev);
- /* Default to 2 channels */
- snd_pcm_hw_constraint_minmax(substream->runtime,
SNDRV_PCM_HW_PARAM_CHANNELS, 2, 2);}
ditto.
Thanks, Charles