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

Pierre-Louis Bossart
2023-05-22T18:32:26Z

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;