On Tue, Sep 23, 2014 at 05:10:02PM -0500, Andy Gross wrote:
> <snip>
>
> > > + break;
> > > + default:
> > > + achan->slave.src_maxburst = 0;
> > > + achan->slave.dst_maxburst = 0;
> > Why clear these for error cases
>
> With the return I shouldn't need to. I'll fix this.
>
> > > + ret = -EINVAL;
> > > + break;
> > > + }
> > > +
> > > + if (!ret)
> > > + writel(achan->blk_size,
> > > + adev->regs + HI_CRCI_CTL(achan->id, adev->ee));
> > and why do we write to HW on this. Shouldn't this be done when you program
> > the descriptor?
>
> It could be deferred to later. The main point is that I don't see the
> slave_config happening every transaction. I was only modifying it now instead
> of making a register write for every transaction.
Well wouldn't it cause a problem if you write to hardware and a transaction
is already in progress.
So it makese sense to write every time at transaction start with latest
value programmed.
> >
> > > +static enum dma_status adm_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
> > > + struct dma_tx_state *txstate)
> > > +{
> > > + struct adm_chan *achan = to_adm_chan(chan);
> > > + struct virt_dma_desc *vd;
> > > + enum dma_status ret;
> > > + unsigned long flags;
> > > + size_t residue = 0;
> > > +
> > > + ret = dma_cookie_status(chan, cookie, txstate);
> > > +
> > Last arg can be null to this, so before you do residue calcluation and block
> > interrupts would make sense to return from here if arg is NULL
>
> Good catch. Will fix.
>
> >
> > > + spin_lock_irqsave(&achan->vc.lock, flags);
> > > +
> > > + vd = vchan_find_desc(&achan->vc, cookie);
> > > + if (vd)
> > > + residue = container_of(vd, struct adm_async_desc, vd)->length;
> > > + else if (achan->curr_txd && achan->curr_txd->vd.tx.cookie == cookie)
> > > + residue = achan->curr_txd->length;
> > so this is current cookie, so you need to read from HW on current position
>
> There is no way to get current position unfortunately without relying on
> unreliable debug registers.
In that case would it make sense to return complete txn length?
--
~Vinod
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