On 06/06/2019 18:25, Dmitry Osipenko wrote: > 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. The ADMA can perform the following transfers (per the CH_CONFIG register) ... MEMORY_TO_MEMORY AHUB_TO_MEMORY MEMORY_TO_AHUB AHUB_TO_AHUB Hence it is possible to use the ADMA to do memory-to-memory transfers that do not involve the ADMAIF. So no the ADMAIF is not part of the ADMA. It is purely the interface to the crossbar (AHUB/APE), but from a hardware standpoint they are separate. And so no we will not amend the hardware description. Jon -- nvpublic
