On 10-01-22, 13:27, Sanjay R Mehta wrote:
> On 1/3/2022 5:04 PM, Vinod Koul wrote:
> > On 17-12-21, 03:58, Sanjay R Mehta wrote:
> >> From: Sanjay R Mehta <sanju.mehta@xxxxxxx>
> >>
> >> The command should be submitted only if the engine is idle,
> >> for this, the next available descriptor is checked and set the flag
> >> to false in case the descriptor is non-empty.
> >>
> >> Also need to segregate the cases when DMA is complete or not.
> >> In case if DMA is already complete there is no need to handle it
> >> again and gracefully exit from the function.
> >>
> >> Signed-off-by: Sanjay R Mehta <sanju.mehta@xxxxxxx>
> >> ---
> >> drivers/dma/ptdma/ptdma-dmaengine.c | 24 +++++++++++++++++-------
> >> 1 file changed, 17 insertions(+), 7 deletions(-)
> >>
> >> diff --git a/drivers/dma/ptdma/ptdma-dmaengine.c b/drivers/dma/ptdma/ptdma-dmaengine.c
> >> index c9e52f6..91b93e8 100644
> >> --- a/drivers/dma/ptdma/ptdma-dmaengine.c
> >> +++ b/drivers/dma/ptdma/ptdma-dmaengine.c
> >> @@ -100,12 +100,17 @@ static struct pt_dma_desc *pt_handle_active_desc(struct pt_dma_chan *chan,
> >> spin_lock_irqsave(&chan->vc.lock, flags);
> >>
> >> if (desc) {
> >> - if (desc->status != DMA_ERROR)
> >> - desc->status = DMA_COMPLETE;
> >> -
> >> - dma_cookie_complete(tx_desc);
> >> - dma_descriptor_unmap(tx_desc);
> >> - list_del(&desc->vd.node);
> >> + if (desc->status != DMA_COMPLETE) {
> >> + if (desc->status != DMA_ERROR)
> >> + desc->status = DMA_COMPLETE;
> >> +
> >> + dma_cookie_complete(tx_desc);
> >> + dma_descriptor_unmap(tx_desc);
> >> + list_del(&desc->vd.node);
> >> + } else {
> >> + /* Don't handle it twice */
> >> + tx_desc = NULL;
> >> + }
> >> }
> >>
> >> desc = pt_next_dma_desc(chan);
> >> @@ -233,9 +238,14 @@ static void pt_issue_pending(struct dma_chan *dma_chan)
> >> struct pt_dma_chan *chan = to_pt_chan(dma_chan);
> >> struct pt_dma_desc *desc;
> >> unsigned long flags;
> >> + bool engine_is_idle = true;
> >>
> >> spin_lock_irqsave(&chan->vc.lock, flags);
> >>
> >> + desc = pt_next_dma_desc(chan);
> >> + if (desc)
> >> + engine_is_idle = false;
> >> +
> >> vchan_issue_pending(&chan->vc);
> >>
> >> desc = pt_next_dma_desc(chan);
> >> @@ -243,7 +253,7 @@ static void pt_issue_pending(struct dma_chan *dma_chan)
> >> spin_unlock_irqrestore(&chan->vc.lock, flags);
> >>
> >> /* If there was nothing active, start processing */
> >> - if (desc)
> >> + if (engine_is_idle)
> >
> > Can you explain why do you need this flag and why desc is not
> > sufficient..
>
> Here it is required to know if the engine was idle or not before
> submitting new desc to the active list (i.e, before calling
> "vchan_issue_pending()" API). So that if there was nothing active then
> start processing this desc otherwise later.
>
> Here desc is submitted to the engine after vchan_issue_pending() API
> called which will actually put the desc into the active list and then if
> I get the next desc, the condition will always be true. Therefore used
> this flag here to solve this issue.
ok
>
> >
> > It also sounds like 2 patches to me...
>
> Once the desc is submitted to the engine that will be handled by
> pt_handle_active_desc() function. This issue was resolved by making
> these changes together. Hence kept into the single patch.
>
> Please suggest to me, if this still needs to be split. I'll make the
> changes accordingly.
2 patches please
--
~Vinod
