[alsa-devel] [topic/asoc][PATCH 0/2] ASoC: OMAP: Add support for mono audio links in McBSP DAI (take #2)
Hi
Second version adding support for mono audio links in OMAP McBSP DAI. At this time, the channels_min is defined to 1 in omap-mcbsp.c and no hacks in machine drivers wanting to use mono link are required.
If channel restrictions are required, then machine driver can use snd_pcm_hw_constraint_minmax. Now only N810 machine driver is affected since all other OMAP machine drivers are using TWL4030 or TLV320AIC23 codecs which all claim to support only 2 channels so the link remains always stereo even playing mono audio.
Prepare for upcoming McBSP DAI update adding support for mono links by restricting number of channels to 2 in N810. This is due tlv320aic3x which claims channels_min = 1 and playing pure mono audio over I2S would cause it to be played only from left channel if both cpu and codec DAI's claim to support mono.
Signed-off-by: Jarkko Nikula jarkko.nikula@nokia.com --- sound/soc/omap/n810.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-)
diff --git a/sound/soc/omap/n810.c b/sound/soc/omap/n810.c index d216b4f..18e2062 100644 --- a/sound/soc/omap/n810.c +++ b/sound/soc/omap/n810.c @@ -70,9 +70,13 @@ static void n810_ext_control(struct snd_soc_codec *codec)
static int n810_startup(struct snd_pcm_substream *substream) { + struct snd_pcm_runtime *runtime = substream->runtime; struct snd_soc_pcm_runtime *rtd = substream->private_data; struct snd_soc_codec *codec = rtd->socdev->codec;
+ snd_pcm_hw_constraint_minmax(runtime, + SNDRV_PCM_HW_PARAM_CHANNELS, 2, 2); + n810_ext_control(codec); return clk_enable(sys_clkout2); }
Patch adds support for mono audio links so that McBSP DAI can operate with real mono codecs. In I2S, the signalling remains the same but only first frame (left channel) is transmitting audio data and second frame having null data. In DSP_A, only first frame is transmitted.
Signed-off-by: Jarkko Nikula jarkko.nikula@nokia.com --- sound/soc/omap/omap-mcbsp.c | 23 ++++++++++++++--------- 1 files changed, 14 insertions(+), 9 deletions(-)
diff --git a/sound/soc/omap/omap-mcbsp.c b/sound/soc/omap/omap-mcbsp.c index 2eeb135..a5b0063 100644 --- a/sound/soc/omap/omap-mcbsp.c +++ b/sound/soc/omap/omap-mcbsp.c @@ -203,7 +203,7 @@ static int omap_mcbsp_dai_hw_params(struct snd_pcm_substream *substream, struct omap_mcbsp_data *mcbsp_data = to_mcbsp(cpu_dai->private_data); struct omap_mcbsp_reg_cfg *regs = &mcbsp_data->regs; int dma, bus_id = mcbsp_data->bus_id, id = cpu_dai->id; - int wlen; + int wlen, channels; unsigned long port;
if (cpu_class_is_omap1()) { @@ -232,12 +232,17 @@ static int omap_mcbsp_dai_hw_params(struct snd_pcm_substream *substream, return 0; }
- switch (params_channels(params)) { + channels = params_channels(params); + switch (channels) { case 2: - /* Set 1 word per (McBPSP) frame and use dual-phase frames */ - regs->rcr2 |= RFRLEN2(1 - 1) | RPHASE; + /* Use dual-phase frames */ + regs->rcr2 |= RPHASE; + regs->xcr2 |= XPHASE; + case 1: + /* Set 1 word per (McBSP) frame */ + regs->rcr2 |= RFRLEN2(1 - 1); regs->rcr1 |= RFRLEN1(1 - 1); - regs->xcr2 |= XFRLEN2(1 - 1) | XPHASE; + regs->xcr2 |= XFRLEN2(1 - 1); regs->xcr1 |= XFRLEN1(1 - 1); break; default: @@ -266,8 +271,8 @@ static int omap_mcbsp_dai_hw_params(struct snd_pcm_substream *substream, regs->srgr1 |= FWID(wlen - 1); break; case SND_SOC_DAIFMT_DSP_A: - regs->srgr2 |= FPER(wlen * 2 - 1); - regs->srgr1 |= FWID(wlen * 2 - 2); + regs->srgr2 |= FPER(wlen * channels - 1); + regs->srgr1 |= FWID(wlen * channels - 2); break; }
@@ -458,13 +463,13 @@ static int omap_mcbsp_dai_set_dai_sysclk(struct snd_soc_dai *cpu_dai, .id = (link_id), \ .type = SND_SOC_DAI_I2S, \ .playback = { \ - .channels_min = 2, \ + .channels_min = 1, \ .channels_max = 2, \ .rates = OMAP_MCBSP_RATES, \ .formats = SNDRV_PCM_FMTBIT_S16_LE, \ }, \ .capture = { \ - .channels_min = 2, \ + .channels_min = 1, \ .channels_max = 2, \ .rates = OMAP_MCBSP_RATES, \ .formats = SNDRV_PCM_FMTBIT_S16_LE, \
On Tue, Nov 25, 2008 at 12:45:07PM +0200, Jarkko Nikula wrote:
Second version adding support for mono audio links in OMAP McBSP DAI. At this time, the channels_min is defined to 1 in omap-mcbsp.c and no hacks in machine drivers wanting to use mono link are required.
If channel restrictions are required, then machine driver can use snd_pcm_hw_constraint_minmax. Now only N810 machine driver is affected since all other OMAP machine drivers are using TWL4030 or TLV320AIC23 codecs which all claim to support only 2 channels so the link remains always stereo even playing mono audio.
Applied both, thanks.
participants (2)
-
Jarkko Nikula -
Mark Brown