lkml.org 
[lkml]   [2019]   [Jun]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] [RFC] dmaengine: add fifo_size member
From
Date
06.06.2019 20:25, Dmitry Osipenko пишет:
> 06.06.2019 19:53, Jon Hunter пишет:
>>
>> On 06/06/2019 17:44, Dmitry Osipenko wrote:
>>> 06.06.2019 19:32, Jon Hunter пишет:
>>>>
>>>> On 06/06/2019 16:18, Dmitry Osipenko wrote:
>>>>
>>>> ...
>>>>
>>>>>>> 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 :)

\
 
 \ /
  Last update: 2019-06-06 19:57    [W:0.103 / U:5.012 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site