> -----Original Message-----
> From: Koul, Vinod
> Sent: Thursday, July 07, 2016 10:29 PM
> To: Jiang, Dave <dave.jiang@xxxxxxxxx>
> Cc: allen.hubbe@xxxxxxx; jdmason@xxxxxxxx; dmaengine@xxxxxxxxxxxxxxx; linux-ntb@xxxxxxxxxxxxxxxx; Williams, Dan J
> <dan.j.williams@xxxxxxxxx>
> Subject: Re: [PATCH v3 1/5] dmaengine: Adding error handling flag
>
> On Tue, Jun 28, 2016 at 04:15:11PM -0700, Dave Jiang wrote:
> > Adding error flag for the call back descriptor to notify upper layer that
> > an error has occurred with this particular DMA op.
> >
> > Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx>
> > ---
> > 0 files changed
> >
> > diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
> > index 0174337..6524881 100644
> > --- a/include/linux/dmaengine.h
> > +++ b/include/linux/dmaengine.h
> > @@ -453,6 +453,20 @@ struct dmaengine_unmap_data {
> > };
> >
> > /**
> > + * enum err_result_flags - result of DMA operations
> > + * @ERR_DMA_NONE - no errors
> > + * @ERR_DMA_READ - DMA read error
> > + * @ERR_DMA_WRITE - DMA write error
> > + * @ERR_DMA_ABORT - Operation aborted
> > + */
> > +enum err_result_flags {
> > + ERR_DMA_NONE = 0,
> > + ERR_DMA_READ,
> > + ERR_DMA_WRITE,
> > + ERR_DMA_ABORT,
> > +};
> > +
> > +/**
> > * struct dma_async_tx_descriptor - async transaction descriptor
> > * ---dma generic offload fields---
> > * @cookie: tracking cookie for this transaction, set to -EBUSY if
> > @@ -480,6 +494,7 @@ struct dma_async_tx_descriptor {
> > dma_async_tx_callback callback;
> > void *callback_param;
> > struct dmaengine_unmap_data *unmap;
> > + enum err_result_flags result;
> > #ifdef CONFIG_ASYNC_TX_ENABLE_CHANNEL_SWITCH
> > struct dma_async_tx_descriptor *next;
> > struct dma_async_tx_descriptor *parent;
>
> Okay this needs more thoughts IMHO. The only issue with this approach is
> that it violates one of the base fundamentals of dmaengine descriptor
> submission.
>
> Client do not touch or use a descriptor after it has been submitted. Looking
> at the results inside descriptor is not right.
>
> Perhaps we can add a query of results in the cookie or add this in
> tx_status, am not sure.
>
> FWIW, we definitely need some kind of error reporting
Ok. Let me think about this some more on how to do this with what you suggested. With XOR/PQ validate, we provide a checksum_result field to check for the result. We could in general have all the DMA submission calls provide something similar for error reporting.
>
> Thanks
> --
> ~Vinod
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