Re: [alsa-devel] [PATCH v2 05/11] ASoC: fsl-ssi: Add support for imx-pcm-fiq

Markus Pargmann wrote:

Add support for non-dma pcm for imx platforms with imx-pcm-fiq support. Instead of imx-pcm-audio, in this case imx-pcm-fiq-audio device is added and the SIER flags are set differently.

So just to be clear, this is interrupt-driven SSI audio? So you're generating an interrupt every time the transmit FIFO goes below the threshold?

I wonder if it makes sense to enable both FIFOs, so that you take half as many interrupts per second.

Signed-off-by: Markus Pargmann mpa@pengutronix.de

sound/soc/fsl/fsl_ssi.c | 70 ++++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 58 insertions(+), 12 deletions(-)

diff --git a/sound/soc/fsl/fsl_ssi.c b/sound/soc/fsl/fsl_ssi.c index 7decbd9..afb5a23 100644 --- a/sound/soc/fsl/fsl_ssi.c +++ b/sound/soc/fsl/fsl_ssi.c @@ -120,10 +120,12 @@ struct fsl_ssi_private {

bool new_binding; bool ssi_on_imx;

• bool dma;

Can you rename this to "use_dma" or something like that?

struct clk *clk; struct platform_device *imx_pcm_pdev; struct imx_pcm_dma_params dma_params_tx; struct imx_pcm_dma_params dma_params_rx;

• struct imx_pcm_fiq_params fiq_params;

  struct { unsigned int rfrc;

@@ -353,7 +355,8 @@ static int fsl_ssi_startup(struct snd_pcm_substream *substream, */

/* Enable the interrupts and DMA requests */

• write_ssi(SIER_FLAGS, &ssi->sier);
  

• if (ssi_private->dma)
  

• 	write_ssi(SIER_FLAGS, &ssi->sier);
  
  

  /*

  • Set the watermark for transmit FIFI 0 and receive FIFO 0. We

@@ -520,6 +523,18 @@ static int fsl_ssi_trigger(struct snd_pcm_substream *substream, int cmd, return -EINVAL; }

• if (!ssi_private->dma) {

• if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
  

• 	write_ssi(CCSR_SSI_SOR_TX_CLR, &ssi->sor);
  

• 	write_ssi(CCSR_SSI_SIER_TIE | CCSR_SSI_SIER_TFE0_EN,
  

• 			&ssi->sier);
  

• } else {
  

• 	write_ssi(CCSR_SSI_SOR_RX_CLR, &ssi->sor);
  

• 	write_ssi(CCSR_SSI_SIER_RIE | CCSR_SSI_SIER_RFF0_EN,
  

• 			&ssi->sier);
  

• }
  

• }
• return 0; }

@@ -680,6 +695,8 @@ static int fsl_ssi_probe(struct platform_device *pdev) sizeof(fsl_ssi_dai_template)); ssi_private->cpu_dai_drv.name = ssi_private->name;

• ssi_private->dma = !of_property_read_bool(np, "fsl,imx-fiq");

Instead of looking for the FIQ property, maybe you should just look for the absence of a DMA property/node, and then default to interrupts if there is no DMA. That would make it more generic, and even work on non-IMX systems.