[AMD Official Use Only - Internal Distribution Only]
> -----Original Message-----
> From: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
> Sent: Wednesday, May 6, 2020 3:29 AM
> To: Alex Deucher <alexdeucher@xxxxxxxxx>; alsa-devel@xxxxxxxxxxxxxxxx;
> broonie@xxxxxxxxxx; Mukunda, Vijendar <Vijendar.Mukunda@xxxxxxx>;
> tiwai@xxxxxxx
> Cc: Deucher, Alexander <Alexander.Deucher@xxxxxxx>
> Subject: Re: [PATCH 07/14] ASoC: amd: add acp3x pdm driver dma ops
>
>
>
> On 5/5/20 3:53 PM, Alex Deucher wrote:
> > From: Vijendar Mukunda <Vijendar.Mukunda@xxxxxxx>
> >
> > This patch adds PDM driver DMA operations.
> >
> > Signed-off-by: Vijendar Mukunda <Vijendar.Mukunda@xxxxxxx>
> > Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
> > ---
> > sound/soc/amd/renoir/acp3x-pdm-dma.c | 199
> +++++++++++++++++++++++++++
> > sound/soc/amd/renoir/rn_acp3x.h | 29 ++++
> > 2 files changed, 228 insertions(+)
> >
> > diff --git a/sound/soc/amd/renoir/acp3x-pdm-dma.c
> b/sound/soc/amd/renoir/acp3x-pdm-dma.c
> > index 4ee47a85e37e..0b5dc49f42c3 100644
> > --- a/sound/soc/amd/renoir/acp3x-pdm-dma.c
> > +++ b/sound/soc/amd/renoir/acp3x-pdm-dma.c
> > @@ -16,6 +16,25 @@
> >
> > #define DRV_NAME "acp_rn_pdm_dma"
> >
> > +static const struct snd_pcm_hardware acp_pdm_hardware_capture = {
> > + .info = SNDRV_PCM_INFO_INTERLEAVED |
> > + SNDRV_PCM_INFO_BLOCK_TRANSFER |
> > + SNDRV_PCM_INFO_BATCH | SNDRV_PCM_INFO_MMAP |
> > + SNDRV_PCM_INFO_MMAP_VALID |
> > + SNDRV_PCM_INFO_PAUSE | SNDRV_PCM_INFO_RESUME,
>
> Can you actually resume from the same position? this seems odd when
> combined with INFO_BATCH which means the position is only precise at
> period boundaries.
>
We used similar flag in Raven APU acp dma driver well.
As per my understanding INFO_BATCH is more about providing period granularity when hw_ptr is queried.
But PDM driver DMA pointer callback returns precise hw_ptr when queried.
Correct me, if understanding is wrong.
> > + .formats = SNDRV_PCM_FMTBIT_S32_LE,
> > + .channels_min = 2,
> > + .channels_max = 2,
> > + .rates = SNDRV_PCM_RATE_48000,
> > + .rate_min = 48000,
> > + .rate_max = 48000,
> > + .buffer_bytes_max = CAPTURE_MAX_NUM_PERIODS *
> CAPTURE_MAX_PERIOD_SIZE,
> > + .period_bytes_min = CAPTURE_MIN_PERIOD_SIZE,
> > + .period_bytes_max = CAPTURE_MAX_PERIOD_SIZE,
> > + .periods_min = CAPTURE_MIN_NUM_PERIODS,
> > + .periods_max = CAPTURE_MAX_NUM_PERIODS,
> > +};
> > +
>
> [...]
>
> > +static snd_pcm_uframes_t acp_pdm_dma_pointer(struct
> snd_soc_component *comp,
> > + struct snd_pcm_substream
> *stream)
> > +{
> > + struct pdm_stream_instance *rtd;
> > + u32 pos, buffersize;
> > + u64 bytescount;
> > +
> > + rtd = stream->runtime->private_data;
> > + pos = 0;
> > + buffersize = 0;
> > + bytescount = 0;
>
> these 3 inits seem unnecessary?
Will remove it.
> > +
> > + buffersize = frames_to_bytes(stream->runtime,
> > + stream->runtime->buffer_size);
> > + bytescount = acp_pdm_get_byte_count(rtd, stream->stream);
> > + if (bytescount > rtd->bytescount)
> > + bytescount -= rtd->bytescount;
> > + pos = do_div(bytescount, buffersize);
> > + return bytes_to_frames(stream->runtime, pos);
> > +}
> > +
