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

["Måns Rullgård" <mans@mansr.com>]

Mason <slash.tmp@free.fr> writes:

> On 25/11/2016 16:12, Måns Rullgård wrote:
>
>> Mason writes:
>> 
>>> I've had several talks with the HW dev, and I don't think they
>>> anticipated the need to mux the 3 channels. In their minds,
>>> customers would choose at most 3 devices to support, and
>>> assign one channel to each device statically.
>>>
>>> In fact, in tango4, supported devices are:
>>> A) NAND Flash controllers 0 and 1
>>> NB: the upstream driver only uses controller 0
>>> B) IDE or SATA controllers 0 and 1
>>> C) a few crypto HW blocks which do not work as expected (unused)
>>>
>>> Customers typically use 1 channel for NAND, maybe 1 for SATA,
>>> and 1 channel remains unused.
>> 
>> The hardware has two sata controllers, and I have a board that uses both.
>
> I don't have the tango3 client devices in mind, but
> 1 NAND + 2 SATA works out alright for 3 channels, right?

There are only two usable channels.

Besides, your 3.4 kernel allocates the channels dynamically, sort of,
but since it has a completely custom api, this particular timing issue
doesn't arise there.

-- 
Måns Rullgård