> From: Dave Jiang <dave.jiang@xxxxxxxxx>
>
> On 4/22/2020 4:22 AM, leonid.ravich@xxxxxxxx wrote:
> > From: Leonid Ravich <Leonid.Ravich@xxxxxxx>
> >
> > completion timeout might trigger unnesesery DMA engine hw reboot in
> > case of missed issue_pending() .
>
> Just curious, are you hitting a use case where this is happening? And what's
> causing the completion timeout?
Unfortunately I did ,
in my case I missed calling dma_async_issue_pending() after few dmaengine_prep_dma_memcpy() due to some error handling bug , timeout timer were still armed due to previous requests (probably) and when finally the timer fired the engine were active (ioat_ring_active()) so it went to reset .
At least this is the theory :).
>
> >
> > Signed-off-by: Leonid Ravich <Leonid.Ravich@xxxxxxx>
> > ---
> > drivers/dma/ioat/dma.c | 7 +++++++
> > 1 file changed, 7 insertions(+)
> >
> > diff --git a/drivers/dma/ioat/dma.c b/drivers/dma/ioat/dma.c index
> > 55a8cf1..2ab07a3 100644
> > --- a/drivers/dma/ioat/dma.c
> > +++ b/drivers/dma/ioat/dma.c
> > @@ -955,6 +955,13 @@ void ioat_timer_event(struct timer_list *t)
> > goto unlock_out;
> > }
> >
> > + /* handle missed issue pending case */
> > + if (ioat_ring_pending(ioat_chan)) {
> > + spin_lock_bh(&ioat_chan->prep_lock);
> > + __ioat_issue_pending(ioat_chan);
> > + spin_unlock_bh(&ioat_chan->prep_lock);
> > + }
> > +
> > set_bit(IOAT_COMPLETION_ACK, &ioat_chan->state);
> > mod_timer(&ioat_chan->timer, jiffies + COMPLETION_TIMEOUT);
> > unlock_out:
> >
