[alsa-devel] [PATCH] ASoC: rockchip: i2s: Support mono capture
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.
Signed-off-by: Matthias Kaehlcke mka@chromium.org --- 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, .channels_max = 2, .rates = SNDRV_PCM_RATE_8000_192000, .formats = (SNDRV_PCM_FMTBIT_S8 | @@ -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; }
The patch
ASoC: rockchip: i2s: Support mono capture
has been applied to the asoc tree at
https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git
All being well this means that it will be integrated into the linux-next tree (usually sometime in the next 24 hours) and sent to Linus during the next merge window (or sooner if it is a bug fix), however if problems are discovered then the patch may be dropped or reverted.
You may get further e-mails resulting from automated or manual testing and review of the tree, please engage with people reporting problems and send followup patches addressing any issues that are reported if needed.
If any updates are required or you are submitting further changes they should be sent as incremental updates against current git, existing patches will not be replaced.
Please add any relevant lists and maintainers to the CCs when replying to this mail.
Thanks, Mark
From db51707b9c9aeedd310ebce60f15d5bb006567e0 Mon Sep 17 00:00:00 2001
From: Matthias Kaehlcke mka@chromium.org Date: Fri, 5 Jan 2018 14:12:42 -0800 Subject: [PATCH] ASoC: rockchip: i2s: Support mono capture
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.
Signed-off-by: Matthias Kaehlcke mka@chromium.org Signed-off-by: Mark Brown broonie@kernel.org --- 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, .channels_max = 2, .rates = SNDRV_PCM_RATE_8000_192000, .formats = (SNDRV_PCM_FMTBIT_S8 | @@ -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; }
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;
On Mon, Jan 08, 2018 at 04:01:15PM -0800, Matthias Kaehlcke wrote:
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.
That seems odd - I'd expect underruns somewhere?
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?
It sounds like a very standard problem with I2S devices, it's a fundamentally stereo format after all. If you can't get it to discard the second channel there's probably not much doing.
participants (2)
-
Mark Brown -
Matthias Kaehlcke