[Sound-open-firmware] [PATCH 2/2] cnl: dma: refine dma interrupt processing on cnl

[Liam Girdwood]

On Thu, 2018-03-08 at 17:47 +0800, rander.wang wrote:
> Hi Liam,
> 
> On 3/8/2018 4:11 PM, Liam Girdwood wrote:
> > On Thu, 2018-03-08 at 14:39 +0800, rander.wang wrote:
> > > hi Liam,
> > > 
> > 
> > Please don't top post.
> > 
> > >       you mentioned :  using IRQ core as 1st level IRQ handler
> > > 
> > > i don't get your idea.  to check which dma triggers the interrupt,
> > > dma
> > > status register
> > > 
> > > would be queried. Do this in 1st level IRQ handler is very ugly.
> > > 
> > > 
> > 
> > 1st level handler does not check the DMAC. It only masks the 1st level
> > IRQ and then calls all the 2nd level handlers. Each second level
> > handler then checks if the IRQ is for itself and returns immediately if
> >   its not the IRQ owner.
> 
>      i have discuss with Keyon. our idea is: maintain a list of 
> interrupt function and private data
> 
>     on second level data structure. In second level interrupt handler, 
> call the irq functions
> 
>     for each list member.
> 
>          can you give some advice?
> 

Btw, the levels I'm referring to here are parent/child level and not priority
level (so it's also worth sending an earlier patch that does some renaming i.e. 
parent_level3_handler -> level2_priority3_handler and IRQ_NUM_EXT_LEVEL2 ->
IRQ_NUM_EXT_PRI2) as this should clear up levels and priorities.
. 

1) 1st level will be DSP interrupt - we then call second level handler..

2) 2nd level will be IRQ controller level (i.e handler will determine which
child HW IP has the IRQ, DMAC, IPC, clock, SSP etc and call the 3rd level child
handler).

3) 3rd level handler will iterate through it's list of client handlers. In this
case it calls the handler for each DMAC.

This means we need the following :-

4) generic level3 handler code needs to be added to
src/platform/cannonlake/interrupt.c. It will be similar to level2 handler in
that it will loop through an array of clients.

5) platform_irq_get_parent() will need modified to support 3rd level handlers.
It will return 3rd level handler for DW DMAC clients.

Does this make sense ?

Liam