@@ -493,11 +493,6 @@ static int bcm2835_i2s_hw_params(struct snd_pcm_substream *substream,
return -EINVAL;
}
- bcm2835_i2s_calc_channel_pos(&rx_ch1_pos, &rx_ch2_pos,
- rx_mask, slot_width, data_delay, odd_slot_offset);
- bcm2835_i2s_calc_channel_pos(&tx_ch1_pos, &tx_ch2_pos,
- tx_mask, slot_width, data_delay, odd_slot_offset);
-
/*
* Transmitting data immediately after frame start, eg
* in left-justified or DSP mode A, only works stable
@@ -508,19 +503,26 @@ static int bcm2835_i2s_hw_params(struct snd_pcm_substream *substream,
"Unstable slave config detected, L/R may be swapped");
/*
- * Set format for both streams.
- * We cannot set another frame length
- * (and therefore word length) anyway,
- * so the format will be the same.
+ * Set format on a per stream basis.
+ * The alignment format can be different depending on direction.
*/
- regmap_write(dev->i2s_regmap, BCM2835_I2S_RXC_A_REG,
- format
- | BCM2835_I2S_CH1_POS(rx_ch1_pos)
- | BCM2835_I2S_CH2_POS(rx_ch2_pos));
- regmap_write(dev->i2s_regmap, BCM2835_I2S_TXC_A_REG,
- format
- | BCM2835_I2S_CH1_POS(tx_ch1_pos)
- | BCM2835_I2S_CH2_POS(tx_ch2_pos));
+ if (substream->stream == SNDRV_PCM_STREAM_CAPTURE) {
+ bcm2835_i2s_calc_channel_pos(&rx_ch1_pos, &rx_ch2_pos,
+ rx_mask, slot_width, data_delay, odd_slot_offset);
+ regmap_write(dev->i2s_regmap, BCM2835_I2S_RXC_A_REG,
+ format
+ | BCM2835_I2S_CH1_POS(rx_ch1_pos)
+ | BCM2835_I2S_CH2_POS(rx_ch2_pos));
+ }
+
+ if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
+ bcm2835_i2s_calc_channel_pos(&tx_ch1_pos, &tx_ch2_pos,
+ tx_mask, slot_width, data_delay, odd_slot_offset);
+ regmap_write(dev->i2s_regmap, BCM2835_I2S_TXC_A_REG,
+ format
+ | BCM2835_I2S_CH1_POS(tx_ch1_pos)
+ | BCM2835_I2S_CH2_POS(tx_ch2_pos));
+ }
/* Setup the I2S mode */
Substream sample alignment was being set in hwparams for both substreams at the same time. This became a problem when the Audio Injector isolated sound card needed to offset sample alignment for high sample rates. The latency difference between playback and capture occurs because of the digital isolation chip propagation time, particularly when the codec is master and the DAC return is twice delayed. This patch sets sample alignment registers based on the substream direction in hwparams. This gives the machine driver more control over sample alignment in the bcm2835 i2s driver. Signed-off-by: Matt Flax <flatmax@flatmax.org> --- sound/soc/bcm/bcm2835-i2s.c | 36 +++++++++++++++++++----------------- 1 file changed, 19 insertions(+), 17 deletions(-)