06.06.2019 20:25, Dmitry Osipenko пишет:

06.06.2019 19:53, Jon Hunter пишет:

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On 06/06/2019 17:44, Dmitry Osipenko wrote:

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06.06.2019 19:32, Jon Hunter пишет:

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On 06/06/2019 16:18, Dmitry Osipenko wrote:

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If I understood everything correctly, the FIFO buffer is shared among
all of the ADMA clients and hence it should be up to the ADMA driver to
manage the quotas of the clients. So if there is only one client that
uses ADMA at a time, then this client will get a whole FIFO buffer, but
once another client starts to use ADMA, then the ADMA driver will have
to reconfigure hardware to split the quotas.

The FIFO quotas are managed by the ADMAIF driver (does not exist in
mainline currently but we are working to upstream this) because it is
this device that owns and needs to configure the FIFOs. So it is really
a means to pass the information from the ADMAIF to the ADMA.

So you'd want to reserve a larger FIFO for an audio channel that has a
higher audio rate since it will perform reads more often. You could also
prioritize one channel over the others, like in a case of audio call for
example.

Is the shared buffer smaller than may be needed by clients in a worst
case scenario? If you could split the quotas statically such that each
client won't ever starve, then seems there is no much need in the
dynamic configuration.

Actually, this is still very much relevant for the static case. Even if
we defined a static configuration of the FIFO mapping in the ADMAIF
driver we still need to pass this information to the ADMA. I don't
really like the idea of having it statically defined in two different
drivers.

Ah, so you need to apply the same configuration in two places. Correct?

Are ADMAIF and ADMA really two different hardware blocks? Or you
artificially decoupled the ADMA driver?

These are two different hardware modules with their own register sets.
Yes otherwise, it would be a lot simpler!

The register sets are indeed separated, but it looks like that ADMAIF is
really a part of ADMA that is facing to Audio Crossbar. No? What is the
purpose of ADMAIF? Maybe you could amend the ADMA hardware description
with the ADMAIF addition until it's too late.

Ugh.. I now regret looking at the TRM. That Audio Processor Engine is a
horrifying beast, it even has FPGA :)