linux-kernel - Re: [PATCH 02/12] soc: qcom: aoss: Drop power domain support

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Date:   Thu, 27 May 2021 23:05:28 -0500
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Sibi Sankar <sibis@...eaurora.org>
Cc:     Stephen Boyd <swboyd@...omium.org>, mathieu.poirier@...aro.org,
        robh+dt@...nel.org, ulf.hansson@...aro.org, rjw@...ysocki.net,
        agross@...nel.org, ohad@...ery.com, linux-arm-msm@...r.kernel.org,
        linux-remoteproc@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, dianders@...omium.org,
        rishabhb@...eaurora.org, sidgup@...eaurora.org
Subject: Re: [PATCH 02/12] soc: qcom: aoss: Drop power domain support

On Tue 27 Apr 01:25 CDT 2021, Sibi Sankar wrote:

> On 2021-04-18 07:31, Stephen Boyd wrote:
> > Quoting Sibi Sankar (2021-04-16 05:03:48)
> > > The load state resources are expected to follow the life cycle of the
> > > remote processor it tracks. However, modeling load state resources as
> > > power-domains result in them getting turned off during system suspend
> > > and thereby falling out of sync with the remote processors that are
> > > still
> > > on. Fix this by replacing load state resource control through the
> > > generic
> > > qmp message send interface instead.
> > > 
> > > Signed-off-by: Sibi Sankar <sibis@...eaurora.org>
> > > ---
> > 
> > Is it possible to keep this code around for a cycle so that there isn't
> > the chance that someone is using the deprecated DT bindings with a new
> > kernel? I worry that ripping the code out will cause them angst.
> 
> deprecated bindings with a newer kernel
> shouldn't cause any problems since it is
> the driver changes that make AOSS PD
> mandatory or not. So the newer kernel will
> just use qmp_send and leave the PD unused.
> 

Maybe I'm missing something in your argument here, but I see two issues:
* The changes here requires that the new qcom,qmp property is defined,
  or the qcom_qmp_get() will be unable to find the qmp instance.
* Between patch 2 and 5 there's no load_state handling.

Perhaps we can carry the power-domain handling as a fallback i
qcom_qmp_get() fails, for a few releases?


Other than the ordering and backwards compatibility issue I think this
looks good. So can you please respin this based on the later revision of
the qmp patch? (And fix Rob's request on the commit message)

https://lore.kernel.org/linux-arm-msm/1620320818-2206-2-git-send-email-deesin@codeaurora.org/

Regards,
Bjorn

> > Certainly we have to keep the code in place until DT is updated, so this
> > patch should come last?
> 
> sure I don't mind, as long as it simplifies
> the merge process.
> 
> -- 
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
> a Linux Foundation Collaborative Project.