Re: [PATCH V2 5/9] ASoC: amd: ps: add support for SoundWire DMA interrupts

On 5/22/23 08:31, Vijendar Mukunda wrote:

Initialize workqueue for SoundWire DMA interrupts handling. Whenever audio data equal to the SoundWire FIFO watermark level are produced/consumed, interrupt is generated. Acknowledge the interrupt and schedule the workqueue.

It would help to explain why a work queue is needed is the first place, as opposed to handling periods in the interrupt thread.

+static void acp63_sdw_dma_workthread(struct work_struct *work) +{

• struct acp63_dev_data *adata = container_of(work, struct acp63_dev_data,

• 				    acp_sdw_dma_work);
  

• struct sdw_dma_dev_data *sdw_dma_data;
• u32 stream_index;
• u16 pdev_index;
• pdev_index = adata->sdw_dma_dev_index;
• sdw_dma_data = dev_get_drvdata(&adata->pdev[pdev_index]->dev);
• for (stream_index = 0; stream_index < ACP63_SDW0_DMA_MAX_STREAMS; stream_index++) {

• if (adata->sdw0_dma_intr_stat[stream_index]) {
  

• 	if (sdw_dma_data->sdw0_dma_stream[stream_index])
  

• 		snd_pcm_period_elapsed(sdw_dma_data->sdw0_dma_stream[stream_index]);
  

• 	adata->sdw0_dma_intr_stat[stream_index] = 0;
  

• }
  

• }
• for (stream_index = 0; stream_index < ACP63_SDW1_DMA_MAX_STREAMS; stream_index++) {

• if (adata->sdw1_dma_intr_stat[stream_index]) {
  

• 	if (sdw_dma_data->sdw1_dma_stream[stream_index])
  

• 		snd_pcm_period_elapsed(sdw_dma_data->sdw1_dma_stream[stream_index]);
  

• 	adata->sdw1_dma_intr_stat[stream_index] = 0;
  

• }
  

• }

I am not clear on the benefits of the workqueue which only tests a flag that's set ...

+}

static irqreturn_t acp63_irq_handler(int irq, void *dev_id) { struct acp63_dev_data *adata; struct pdm_dev_data *ps_pdm_data; struct amd_sdw_manager *amd_manager; u32 ext_intr_stat, ext_intr_stat1;

• u32 stream_id = 0; u16 irq_flag = 0;

• u16 sdw_dma_irq_flag = 0; u16 pdev_index;

• u16 index;

  adata = dev_id; if (!adata)

@@ -148,7 +178,57 @@ static irqreturn_t acp63_irq_handler(int irq, void *dev_id) snd_pcm_period_elapsed(ps_pdm_data->capture_stream); irq_flag = 1; }

• if (irq_flag)

• if (ext_intr_stat & ACP_SDW_DMA_IRQ_MASK) {

• for (index = ACP_AUDIO2_RX_THRESHOLD; index <= ACP_AUDIO0_TX_THRESHOLD; index++) {
  

• 	if (ext_intr_stat & BIT(index)) {
  

• 		writel(BIT(index), adata->acp63_base + ACP_EXTERNAL_INTR_STAT);
  

• 		switch (index) {
  

• 		case ACP_AUDIO0_TX_THRESHOLD:
  

• 			stream_id = ACP_SDW0_AUDIO0_TX;
  

• 			break;
  

• 		case ACP_AUDIO1_TX_THRESHOLD:
  

• 			stream_id = ACP_SDW0_AUDIO1_TX;
  

• 			break;
  

• 		case ACP_AUDIO2_TX_THRESHOLD:
  

• 			stream_id = ACP_SDW0_AUDIO2_TX;
  

• 			break;
  

• 		case ACP_AUDIO0_RX_THRESHOLD:
  

• 			stream_id = ACP_SDW0_AUDIO0_RX;
  

• 			break;
  

• 		case ACP_AUDIO1_RX_THRESHOLD:
  

• 			stream_id = ACP_SDW0_AUDIO1_RX;
  

• 			break;
  

• 		case ACP_AUDIO2_RX_THRESHOLD:
  

• 			stream_id = ACP_SDW0_AUDIO2_RX;
  

• 			break;
  

• 		}
  

• 		adata->sdw0_dma_intr_stat[stream_id] = 1;
  

.. here ...

• 		sdw_dma_irq_flag = 1;
  

• 	}
  

• }
  

• }
• /* SDW1 BT RX */
• if (ext_intr_stat1 & ACP_P1_AUDIO1_RX_THRESHOLD) {

• writel(ACP_P1_AUDIO1_RX_THRESHOLD,
  

•        adata->acp63_base + ACP_EXTERNAL_INTR_STAT1);
  

• adata->sdw1_dma_intr_stat[ACP_SDW1_AUDIO1_RX] = 1;
  

... and here ...

• sdw_dma_irq_flag = 1;
  

• }
• /* SDW1 BT TX*/
• if (ext_intr_stat1 & ACP_P1_AUDIO1_TX_THRESHOLD) {

• writel(ACP_P1_AUDIO1_TX_THRESHOLD,
  

•        adata->acp63_base + ACP_EXTERNAL_INTR_STAT1);
  

• adata->sdw1_dma_intr_stat[ACP_SDW1_AUDIO1_TX] = 1;
  

... or here ...

• sdw_dma_irq_flag = 1;
  

• }
• if (sdw_dma_irq_flag)

• schedule_work(&adata->acp_sdw_dma_work);
  

• if (irq_flag || sdw_dma_irq_flag) return IRQ_HANDLED; else return IRQ_NONE;