El Fri, Jan 05, 2018 at 02:12:42PM -0800 Matthias Kaehlcke ha dit:
The Rockchip I2S controller only allows to configure even numbers of capture channels. It is still possible to capture monophonic audio by using dual-channel mode and ignoring the 'data' from the second channel.
Due to different issues in our audio recording path I couldn't test this properly, and only looked at the .wav data in audacity, which appeared to look ok. After putting some of the missing pieces together and I noticed that mono capture doesn't work as intended, the recorded audio is slowed down. I think this is because the I2S controller keeps generating a two-channel stream, however the sound system interprets it as a monophonic stream because of the channel configuration.
Not sure if there is a clean solution for this if we can't tell the hardware to generate a single-channel stream. Any suggestions or do we have to revert the patch?
Sorry about the mess :(
sound/soc/rockchip/rockchip_i2s.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/sound/soc/rockchip/rockchip_i2s.c b/sound/soc/rockchip/rockchip_i2s.c index 908211e1d6fc..cc22ab3d10dd 100644 --- a/sound/soc/rockchip/rockchip_i2s.c +++ b/sound/soc/rockchip/rockchip_i2s.c @@ -328,6 +328,7 @@ static int rockchip_i2s_hw_params(struct snd_pcm_substream *substream, val |= I2S_CHN_4; break; case 2:
- case 1: val |= I2S_CHN_2; break; default:
@@ -460,7 +461,7 @@ static struct snd_soc_dai_driver rockchip_i2s_dai = { }, .capture = { .stream_name = "Capture",
.channels_min = 2,
.channels_min = 1,@@ -654,7 +655,7 @@ static int rockchip_i2s_probe(struct platform_device *pdev) }
if (!of_property_read_u32(node, "rockchip,capture-channels", &val)) {
if (val >= 2 && val <= 8)
if (val >= 1 && val <= 8) soc_dai->capture.channels_max = val;