On Thu, Jun 15, 2017 at 08:19:48PM +0530, Sricharan R wrote:
> > I am not sure why suppressing callback helps? I think you should still
> > continue filling up FIFO but also ensure interrupt so that callback can be
> > invoked, user thread maybe waiting on that
> >
> > FWIW waiting for interrupt and submitting is extremely inefficient and
> > shouldn't be done, so that part of this is good.
> >
>
> Thanks for the review.
>
> So one part is, adding desc to the FIFO till its full, so the BAM dmaengine
> is
> busy when there are pending descriptors without waiting for interrupt.
>
> Another part is, currently, the driver signals the completion of the each
> descriptor with a interrupt, even though the client has not requested
> a DMA_PREP_INTERRUPT/registered a callback. Instead if the client has
> not requested for a interrupt for the completion of a descriptor, then
> generate a interrupt only for descriptor for which it was requested and
> also complete all the previous descriptors in that interrupt (means call
> all callbacks). So we still call all callbacks but at the end of a
> group of descriptors.
okay that sounds sane, but somehow I was getting the impression that we
might be suppressing, so you might want to update comments
> >> async_desc->num_desc = num_alloc;
> >> async_desc->curr_desc = async_desc->desc;
> >> @@ -680,13 +684,18 @@ static struct dma_async_tx_descriptor
> >> *bam_prep_slave_sg(struct dma_chan *chan,
> >> static int bam_dma_terminate_all(struct dma_chan *chan)
> >> {
> >> struct bam_chan *bchan = to_bam_chan(chan);
> >> + struct bam_async_desc *async_desc;
> >> unsigned long flag;
> >> LIST_HEAD(head);
> >>
> >> /* remove all transactions, including active transaction */
> >> spin_lock_irqsave(&bchan->vc.lock, flag);
> >> if (bchan->curr_txd) {
> >> - list_add(&bchan->curr_txd->vd.node, &bchan->vc.desc_issued);
> >> + list_for_each_entry(async_desc, &bchan->desc_list, desc_node) {
> >> + bchan->curr_txd = async_desc;
> >> + list_add(&bchan->curr_txd->vd.node,
> >> + &bchan->vc.desc_issued);
> >
> > that is wrong, terminated should not add to issued list
>
> hmm, since it was already done like that, i added the same for list of
> descriptors now.
Sounds like you should fix existing behaviour too :)
--
~Vinod
