On 14/02/17 20:32, Charles Keepax wrote:
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.
Actually, I didn't think of this, but there is no reason to have 2 channels available in DSP A mode with codec master. I will change this to constrain the channels to 8.
- 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.
Will do.
}
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.
Will do.
Thanks, Charles