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To: Baochen Qiang <>
Subject: Re: [PATCH v2] bus: mhi: Wait for M2 state during system resume
Date: Tue, 20 Jul 2021 02:30:50 +0000	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>


This patch was applied to qcom/linux.git (refs/heads/for-next):

On Mon, 24 May 2021 12:03:12 +0800 you wrote:
> During system resume, MHI host triggers M3->M0 transition and then waits
> for target device to enter M0 state. Once done, the device queues a state
> change event into ctrl event ring and notifies MHI host by raising an
> interrupt, where a tasklet is scheduled to process this event. In most cases,
> the tasklet is served timely and wait operation succeeds.
> However, there are cases where CPU is busy and cannot serve this tasklet
> for some time. Once delay goes long enough, the device moves itself to M1
> state and also interrupts MHI host after inserting a new state change
> event to ctrl ring. Later CPU finally has time to process the ring, however
> there are two events in it now:
> 	1. for M3->M0 event, which is processed first as queued first,
> 	   tasklet handler updates device state to M0 and wakes up the task,
> 	   i.e., the MHI host.
> 	2. for M0->M1 event, which is processed later, tasklet handler
> 	   triggers M1->M2 transition and updates device state to M2 directly,
> 	   then wakes up the MHI host(if still sleeping on this wait queue).
> Note that although MHI host has been woken up while processing the first
> event, it may still has no chance to run before the second event is processed.
> In other words, MHI host has to keep waiting till timeout cause the M0 state
> has been missed.
> [...]

Here is the summary with links:
  - [v2] bus: mhi: Wait for M2 state during system resume

You are awesome, thank you!
Deet-doot-dot, I am a bot.

      parent reply	other threads:[~2021-07-20  2:42 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-24  4:03 Baochen Qiang
2021-05-24  4:15 ` Manivannan Sadhasivam
2021-05-24  4:37 ` Manivannan Sadhasivam
2021-05-24  4:58   ` Manivannan Sadhasivam
2021-05-24  7:01 ` Greg KH
2021-05-24  8:43   ` Manivannan Sadhasivam
2021-07-20  2:30 ` patchwork-bot+linux-arm-msm [this message]

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