Hi Albert
On 3/14/2024 3:29 AM, Albert Wang wrote:
On Thu, Mar 14, 2024 at 3:18 AM Wesley Cheng <quic_wcheng@xxxxxxxxxxx> wrote:
Hi Albert,
On 3/13/2024 1:03 AM, Albert Wang wrote:
Hi Wesley,
The suspend function `qc_usb_audio_offload_suspend()` looks to stop
the traffic on the bus, so that the bus can be suspended. That allows
the application processor(AP) to enter suspend. There is a subtle
difference with our feature, which is to allow AP suspend with the
Host and USB controller active to continue the audio offloading. We
call this feature `allow AP suspend in playback`. So, I have some
points to clarify with you:
Yes, I'm aware of that feature also.
1. Will the suspend flow `usb_audio_suspend() -->
platform_ops->suspend_cb() --> qc_usb_audio_offload_suspend()` be
called when offloading is active?
It can be. This is why in our case, we are going to issue the
disconnect event to the audio DSP to stop the session if it is currently
in one.
2. As my understanding, the suspend function is to allow AP suspend
when the offloading is IDLE, but it won't allow AP suspend when in
playback or capture. Please correct me if anything is wrong.
As mentioned above, it will let apps go into PM suspend after forcing
the audio stream to be idle. We won't block PM suspend entry.
Right. Your design is to force the audio stream idle, or say, inform
the audio DSP
to stop the current offloading session first, then AP can go into PM
suspend as usual.
Then I can say the current design did not support the `allow AP
suspend in playback`
feature, right?
Correct, this series does not cover this mechanism.
Yes, I saw that patch as well. I'll take a look once this series lands
upstream.
That patch is rejected and archived now. So we need to find another
approach to do
that, even based on your framework.
We can discuss that offline and come up with an approach that is
reviewable by maintainers and the community.
Thanks
Wesley Cheng
Thanks,
Albert
3. We would like to integrate the `allow AP suspend in playback`
feature with your framework to become one upstream offload solution.
Here is the patch:
https://patchwork.kernel.org/project/linux-pm/patch/20240223143833.1509961-1-guanyulin@xxxxxxxxxx/
.
Yes, I saw that patch as well. I'll take a look once this series lands
upstream.
Thanks
Wesley Cheng
