Re: [PATCH v2 2/2] dmaengine: Add DW AXI DMAC driver

From	Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2 2/2] dmaengine: Add DW AXI DMAC driver
Date	2017-04-26 17:30 +0200
Message-ID	<tAx3d-46S-43@gated-at.bofh.it> (permalink)
References	(4 earlier) <tyKed-8vc-3@gated-at.bofh.it> <tzOz9-q9-47@gated-at.bofh.it> <tzPvb-118-15@gated-at.bofh.it> <tAaq0-6oY-87@gated-at.bofh.it> <tAdea-88w-3@gated-at.bofh.it>
Organization	Intel Finland Oy

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On Tue, 2017-04-25 at 21:12 +0300, Andy Shevchenko wrote:
> On Tue, 2017-04-25 at 15:16 +0000, Eugeniy Paltsev wrote:
> > On Mon, 2017-04-24 at 19:56 +0300, Andy Shevchenko wrote:
> > > On Mon, 2017-04-24 at 15:55 +0000, Eugeniy Paltsev wrote:

> > > Descriptor is active until terminate_all() is called or new
> > > descriptor
> > > is supplied. So, the caller has a quite time to check on it.
> > > 
> > > So, what's wrong on it by your opinion?
> > 
> > Hmm, this looks OK. (In my example (hsu/hsu.c driver) error
> > descriptors
> > are not freed even after terminate_all is called)
> 
> If it's active it will be freed.
> Otherwise caller should check somewhere that descriptor fails.
> 
> But actually this is fragile and we need to monitor failed
> descriptors.
> Thanks for reporting.
> 
> > 
> > > Of course, if you want to keep by some reason (should be stated
> > > what
> > > the reason in comment) erred descriptors, you can do that.
> > 
> > So, I'll create desc_error list and store failed descriptors in this
> > list until terminate_all() is called.
> > Is it OK implementation?
> 
> Nope, we need to amend virt-chan API for that. I'm on it. Will send a
> series soon.

I have to correct what I wrote before.

We have two options:
a) one I proposed above;
b) move descriptor to complete list and call complete callback with
result.

So, it looks like the b) variant is what is done already in 4 (did I
calculate correctly?) drivers and respective users.

-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy

Thread

Re: [PATCH v2 2/2] dmaengine: Add DW AXI DMAC driver Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com> - 2017-04-25 17:20 +0200
  Re: [PATCH v2 2/2] dmaengine: Add DW AXI DMAC driver Andy Shevchenko <andriy.shevchenko@linux.intel.com> - 2017-04-25 20:20 +0200
    Re: [PATCH v2 2/2] dmaengine: Add DW AXI DMAC driver Andy Shevchenko <andriy.shevchenko@linux.intel.com> - 2017-04-26 17:30 +0200
      Re: [PATCH v2 2/2] dmaengine: Add DW AXI DMAC driver Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com> - 2017-04-27 15:30 +0200
        Re: [PATCH v2 2/2] dmaengine: Add DW AXI DMAC driver Andy Shevchenko <andriy.shevchenko@linux.intel.com> - 2017-04-27 15:40 +0200
    Re: [PATCH v2 2/2] dmaengine: Add DW AXI DMAC driver Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com> - 2017-04-27 17:40 +0200

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