Re: [RESEND PATCH v6 2/4] media: chips-media: wave5: Support runtime suspend/resume

[Devarsh Thakkar]

Hi Nicolas,

On 20/06/24 19:35, Nicolas Dufresne wrote:
> Hi Devarsh,
> 
> Le jeudi 20 juin 2024 à 15:05 +0530, Devarsh Thakkar a écrit :
>> In my view the delayed suspend functionality is generally helpful for devices
>> where resume latencies are higher for e.g. this light sensor driver [2] uses
>> it because it takes 250ms to stabilize after resumption and I don't see this
>> being used in codec drivers generally since there is no such large resume
>> latency. Please let me know if I am missing something or there is a strong
>> reason to have delayed suspend for wave5.
> 
> It sounds like you did proper scientific testing of the suspend results calls,
> mind sharing the actual data ?

Nopes, I did not do that but yes I agree it is good to profile and evaluate
the trade-off but I am not expecting 250ms kind of latency. I would suggest
Jackson to do the profiling for the resume latencies.

But perhaps a separate issue, I did notice that intention of the patchset was
to suspend without waiting for the timeout if there is no application having a
handle to the wave5 device but even if I close the last instance I still see
the IP stays on for 5seconds as seen in this logs [1] and this perhaps could
be because extra pm counter references being hold.

[2024-06-20 12:32:50] Freeing pipeline ...

and after 5 seconds..

[2024-06-20 12:32:55] |   204     | AM62AX_DEV_CODEC0 | DEVICE_STATE_ON |
[2024-06-20 12:32:56] |   204     | AM62AX_DEV_CODEC0 | DEVICE_STATE_OFF

[1]: https://gist.github.com/devarsht/009075d8706001f447733ed859152d90

Regards
Devarsh