Re: [PATCH 6/7] ASoC: renesas: rz-ssi: Use generic PCM dmaengine APIs

[Claudiu Beznea]

Hi, Geert,

On 1/26/26 16:26, Geert Uytterhoeven wrote:
> Hi Claudiu,
>
> On Mon, 26 Jan 2026 at 11:32, Claudiu <claudiu.beznea@xxxxxxxxx> wrote:
> > From: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx>
> >
> > On Renesas RZ/G2L and RZ/G3S SoCs (where this was tested), captured audio
> > files occasionally contained random spikes when viewed with a profiling
> > tool such as Audacity. These spikes were also audible as popping noises.
> >
> > Using cyclic DMA resolves this issue. The driver was reworked to use the
> > existing support provided by the generic PCM dmaengine APIs. In addition
> > to eliminating the random spikes, the following issues were addressed:
> > - blank periods at the beginning of recorded files, which occurred
> >    intermittently, are no longer present
> > - no overruns or underruns were observed when continuously recording
> >    short audio files (e.g. 5 seconds) in a loop
> > - concurrency issues in the SSI driver when enqueuing DMA requests were
> >    eliminated; previously, DMA requests could be prepared and submitted
> >    both from the DMA completion callback and the interrupt handler, which
> >    led to crashes after several hours of testing
> > - the SSI driver logic is simplified
> > - the number of generated interrupts is reduced by approximately 250%
> >
> > In the SSI platform driver probe function, the following changes were
> > made:
> > - the driver-specific DMA configuration was removed in favor of the
> >    generic PCM dmaengine APIs. As a result, explicit cleanup goto labels
> >    are no longer required and the driver remove callback was dropped,
> >    since resource management is now handled via devres helpers
> > - special handling was added for IP variants operating in half-duplex
> >    mode, where the DMA channel name in the device tree is "rt"; this DMA
> >    channel name is taken into account and passed to the generic PCM
> >    dmaengine configuration data
> >
> > All code previously responsible for preparing and completing DMA
> > transfers was removed, as this functionality is now handled entirely by
> > the generic PCM dmaengine APIs.
> >
> > Since DMA channels must be paused and resumed during recovery paths
> > (overruns and underruns), the DMA channel references are stored in
> > rz_ssi_hw_params().
> >
> > The logic in rz_ssi_is_dma_enabled() was updated to reflect that the
> > driver no longer manages DMA transfers directly.
> >
> > Finally, rz_ssi_stream_is_play() was removed, as it had only a single
> > remaining user after this rework, and its logic was inlined at the call
> > site.
> >
> > Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx>
>
> Thanks for your patch!
>
> > --- a/sound/soc/renesas/rz-ssi.c
> > +++ b/sound/soc/renesas/rz-ssi.c
>
> > @@ -1116,15 +936,19 @@ static struct snd_soc_dai_driver rz_ssi_soc_dai[] = {
> >   static const struct snd_soc_component_driver rz_ssi_soc_component = {
> >          .name                   = "rz-ssi",
> >          .open                   = rz_ssi_pcm_open,
> > -       .pointer                = rz_ssi_pcm_pointer,
> > -       .pcm_construct          = rz_ssi_pcm_new,
> >          .legacy_dai_naming      = 1,
> >   };
> >
> > +static struct snd_dmaengine_pcm_config rz_ssi_dmaegine_pcm_conf = {
> > +       .prepare_slave_config   = snd_dmaengine_pcm_prepare_slave_config,
>
> This fails to link if CONFIG_SND_SOC_GENERIC_DMAENGINE_PCM is not
> enabled (e.g. renesas_defconfig):
>
>      aarch64-linux-gnu-ld: sound/soc/renesas/rz-ssi.o: in function
> `rz_ssi_probe':
>      rz-ssi.c:(.text+0x538): undefined reference to
> `devm_snd_dmaengine_pcm_register'
>      aarch64-linux-gnu-ld: sound/soc/renesas/rz-ssi.o:(.data+0xc8):
> undefined reference to `snd_dmaengine_pcm_prepare_slave_config'
>
> Adding a select like this white-space damaged snippet:
>
>      --- a/sound/soc/renesas/Kconfig
>      +++ b/sound/soc/renesas/Kconfig
>      @@ -56,6 +56,7 @@ config SND_SOC_MSIOF
>       config SND_SOC_RZ
>              tristate "RZ/G2L series SSIF-2 support"
>              depends on ARCH_RZG2L || COMPILE_TEST
>      +       select SND_SOC_GENERIC_DMAENGINE_PCM
>              help
>                This option enables RZ/G2L SSIF-2 sound support.
>
> would fix the build.

Thank you for reporting and proposing a fix. I'll take care of it in v2.

Claudiu