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

[Frank Li <Frank.li@oss.nxp.com>]

On Fri, Jul 24, 2026 at 01:50:44PM +0900, Koichiro Den wrote:
> On Thu, Jul 23, 2026 at 11:57:32AM -0500, Frank Li wrote:
> > 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?
>
> This is a prep, non-functional change for patch 9. Patch 9 first invokes

Okay, just commit message show it prepare for ...

Frank

> dw_edma_ll_consume_progress(), which may complete and remove the last issued
> descriptor.  Even then, the switch still has work to do for each request state,
> so it can no longer be guarded by 'if (vd)'.
>
> I split this reordering (non-functional change) out only to keep the functional
> diff in patch 9 readable and easier to review.
>
> Best regards,
> Koichiro
>
> >
> > Frank
> > >
> > > No functional change intended.
> > >
> > > Signed-off-by: Koichiro Den <den@valinux.co.jp>
> > > ---
> > > 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
> > >