[FEATURE] Extend zephyr_ll to get its LL system tick from the DMA IRQ #4523

Activity

1. iuliana-prodan

   added

   enhancementNew feature or requestNew feature or request

   on Jul 21, 2021
2. iuliana-prodan

   assigned

   iuliana-prodan

   ,

   lyakh

   ,

   kv2019i

   ,

   lgirdwood

   and

   marc-hb

   on Jul 21, 2021
3. marc-hb

   changed the title [-][FEATURE] Extend zephy_ll to get its LL system tick from the DMA IRQ[/-] [+][FEATURE] Extend zephyr_ll to get its LL system tick from the DMA IRQ[/+] on Jul 22, 2021
4. marc-hb commented on Jul 22, 2021

   

   marc-hb

   on Jul 22, 2021

   Collaborator

   More actions

   From #4503

   in i.MX case, we don't want to use zephyr_ll since this is limited to TIMER_DOMAIN (see here) and we are using DMA_DOMAIN. We want, for now, to keep using ll_schedule.

   so DMA domain is becoming problematic as it does not scale well to multiple low latency streams (it's simple and great when there is a smaller number of streams though) or when the codec is driving the clocks.
   I think we need to improve the DMA driven domain as follows.

   Today we have

   Zephyr LL gets its LL system tick from the timer. This runs in IRQ context and is non preemtable.
   LL system tick wakes up high priority LL thread.
   LL thread executes pipeline work.
   We need to make one change to support DMA domain here and make it synchronous. Step 1 should also be able to be

   Zephyr LL gets its LL system tick from the DMA IRQ. This runs in IRQ context and is non preemtable.
   This means we keep the DMA based time domain and we can also scale all LL streams to this time domain.

   Fwiw, this is how things worked on OMAP4, the topology would tell FW which DMA channel was to be used as time domain. If the DMA channel stopped then FW had to then use the DMA channel from the next running stream. PR #4471 is allowing the trigger(start|stops) to be synchronised and this would mean that DMA IRQs could also be synchronised.
5. marc-hb commented on Mar 9, 2023

   

   marc-hb

   on Mar 9, 2023

   Collaborator

   More actions

   @lyakh is this still relevant?
6. dbaluta commented on Mar 10, 2023

   

   dbaluta

   on Mar 10, 2023

   Collaborator

   More actions

   This feature is implemented under CONFIG_DMA_DOMAIN.
7. dbaluta

   closed this as completedon Mar 10, 2023