Re: Tearing down DMA transfer setup after DMA client has finished

[Måns Rullgård]

Mason <slash.tmp@xxxxxxx> writes:

> On 25/11/2016 15:12, Måns Rullgård wrote:
>
>> Mason writes:
>> 
>>> On 25/11/2016 12:57, Måns Rullgård wrote:
>>>
>>>> The same DMA unit is also used for SATA, which is an off the shelf
>>>> Designware controller with an in-kernel driver.  This interrupt timing
>>>> glitch can actually explain some intermittent errors I've observed with
>>>> it.
>>>
>>> FWIW, newer chips embed an AHCI controller, with a dedicated
>>> memory channel.
>>>
>>> FWIW2, the HW dev said memory channels are "almost free", and he
>>> would have no problem giving each device their own private channel
>>> read/write pair.
>> 
>> We still need to deal with the existing hardware.
>
> Can you confirm that your MBUS driver, in its current form,
> does not support memcpy-type transfers, which generate two
> IRQs (one from send agent, one from receive agent)?

It does not.

> Do you plan to support that, or is it just too quirky?

I hadn't planned on doing that, but I'm ruling it out entirely.

-- 
Måns Rullgård