Re: [PATCH v2 07/19] dmaengine: dw-edma: Dispatch DONE interrupts by channel request

On Thu, Jul 23, 2026 at 05:41:38PM +0900, Koichiro Den wrote:

Subject:

Check channel request firstly at DONE channel interrupts ?

> Handle the channel request first in the DONE interrupt path, then look
> at the issued descriptor list only in the cases that need it.
>
> This keeps the existing behavior, including the current STOP and PAUSE
> handling when no issued descriptor is present.

Need descript why need this change?

Frank
>
> No functional change intended.
>
> Signed-off-by: Koichiro Den <[email protected]>
> ---
> Changes in v2:
>   - Limit this patch to request dispatch with no functional change;
>     move LL progress and empty-issued-list handling to later patches.
>
>  drivers/dma/dw-edma/dw-edma-core.c | 60 +++++++++++++++---------------
>  1 file changed, 31 insertions(+), 29 deletions(-)
>
> diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c
> index 29f78405e9fb..fa104af4146e 100644
> --- a/drivers/dma/dw-edma/dw-edma-core.c
> +++ b/drivers/dma/dw-edma/dw-edma-core.c
> @@ -682,41 +682,43 @@ static void dw_edma_done_interrupt(struct dw_edma_chan *chan)
>  		return;
>  	}
>
> -	vd = vchan_next_desc(&chan->vc);
> -	if (vd) {
> -		switch (chan->request) {
> -		case EDMA_REQ_NONE:
> -		case EDMA_REQ_PAUSE:
> -			desc = vd2dw_edma_desc(vd);
> -			if (desc->start_burst >= desc->nburst) {
> -				dw_hdma_set_callback_result(vd,
> -							    DMA_TRANS_NOERROR);
> -				list_del(&vd->node);
> -				vchan_cookie_complete(vd);
> -				if (!chan->non_ll)
> -					chan->ll_end = chan->ll_head;
> -			}
> -
> -			if (chan->request == EDMA_REQ_PAUSE) {
> -				chan->request = EDMA_REQ_NONE;
> -				chan->status = EDMA_ST_PAUSE;
> -				break;
> -			}
> -
> -			/* Continue transferring if there are remaining chunks or issued requests.
> -			 */
> -			chan->status = dw_edma_start_transfer(chan) ? EDMA_ST_BUSY : EDMA_ST_IDLE;
> +	switch (chan->request) {
> +	case EDMA_REQ_NONE:
> +	case EDMA_REQ_PAUSE:
> +		vd = vchan_next_desc(&chan->vc);
> +		if (!vd)
>  			break;
>
> -		case EDMA_REQ_STOP:
> -			dw_edma_terminate_all_descs(chan);
> +		desc = vd2dw_edma_desc(vd);
> +		if (desc->start_burst >= desc->nburst) {
> +			dw_hdma_set_callback_result(vd, DMA_TRANS_NOERROR);
> +			list_del(&vd->node);
> +			vchan_cookie_complete(vd);
> +			if (!chan->non_ll)
> +				chan->ll_end = chan->ll_head;
> +		}
> +
> +		if (chan->request == EDMA_REQ_PAUSE) {
>  			chan->request = EDMA_REQ_NONE;
> -			chan->status = EDMA_ST_IDLE;
> +			chan->status = EDMA_ST_PAUSE;
>  			break;
> +		}
>
> -		default:
> +		chan->status = dw_edma_start_transfer(chan) ? EDMA_ST_BUSY : EDMA_ST_IDLE;
> +		break;
> +
> +	case EDMA_REQ_STOP:
> +		vd = vchan_next_desc(&chan->vc);
> +		if (!vd)
>  			break;
> -		}
> +
> +		dw_edma_terminate_all_descs(chan);
> +		chan->request = EDMA_REQ_NONE;
> +		chan->status = EDMA_ST_IDLE;
> +		break;
> +
> +	default:
> +		break;
>  	}
>  	spin_unlock_irqrestore(&chan->vc.lock, flags);
>  }
> --
> 2.51.0
>