linux-kernel - Re: [PATCH v2 3/3] bus: mhi: core: Process execution environment changes serially

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Message-ID: <02206c10-f44f-bf6a-91ce-3cff8e7d0ea8@codeaurora.org>
Date:   Fri, 15 Jan 2021 11:02:28 -0800
From:   Hemant Kumar <hemantk@...eaurora.org>
To:     Bhaumik Bhatt <bbhatt@...eaurora.org>,
        manivannan.sadhasivam@...aro.org
Cc:     linux-arm-msm@...r.kernel.org, carl.yin@...ctel.com,
        naveen.kumar@...ctel.com, jhugo@...eaurora.org,
        linux-kernel@...r.kernel.org, loic.poulain@...aro.org
Subject: Re: [PATCH v2 3/3] bus: mhi: core: Process execution environment
 changes serially



On 1/14/21 11:16 AM, Bhaumik Bhatt wrote:
> In current design, whenever the BHI interrupt is fired, the execution
> environment is updated. This can cause race conditions and impede any
> ongoing power up/down processing. For example, if a power down is in
> progress and the host has updated the execution environment to a
> local "disabled" state, any BHI interrupt firing later could replace
> it with the value from the BHI EE register.
Can we add what is the real issue observed when mhi_cntrl->ee changed in 
above scenario?
  Another example would be
> that the device can enter mission mode while device creation for SBL
> is still going on, leading to multiple attempts at opening the same
> channel.
Even for this scenario, can we add the real issue that was observed e.g. 
same device was attempting to get created twice and caused xyz issue?
> 
> Ensure that EE changes are handled only from appropriate places and
> occur one after another and handle only PBL or RDDM EE changes as
> critical events directly from the interrupt handler. This also makes
> sure that we use the correct execution environment to notify the
> controller driver when the device resets to one of the PBL execution
> environments.
> 
[..]

Thanks,
Hemant
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