linux-kernel - Re: [PATCH] soc: qcom: pmic

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Message-ID: <ZXsKzsij3Xb50Ap9@hovoldconsulting.com>
Date:   Thu, 14 Dec 2023 15:01:50 +0100
From:   Johan Hovold <johan@...nel.org>
To:     Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc:     Rob Clark <robdclark@...il.com>, linux-arm-msm@...r.kernel.org,
        Rob Clark <robdclark@...omium.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] soc: qcom: pmic_glink: Fix boot when QRTR=m

On Thu, Dec 14, 2023 at 01:04:43PM +0200, Dmitry Baryshkov wrote:
> On Thu, 14 Dec 2023 at 09:16, Johan Hovold <johan@...nel.org> wrote:
> >
> > On Wed, Dec 13, 2023 at 01:06:43PM -0800, Rob Clark wrote:
> > > From: Rob Clark <robdclark@...omium.org>
> > >
> > > We need to bail out before adding/removing devices, if we are going
> > > to -EPROBE_DEFER.  Otherwise boot will get stuck forever at
> > > deferred_probe_initcall().
> >
> > Can please you expand on why this is a problem here in the commit
> > message?
> >
> > The aux devices appear to be tore down correctly in the probe error
> > paths so how exactly does that lead to deferred_probe_initcall() being
> > stuck? This sounds like we may have a problem elsewhere which this patch
> > is papering over.
> 
> This is a known problem. Successful probes during the probe deferral
> loop causes the whole loop to be reiterated. Creating child devices
> usually results in  a successful probe. Aso I thought that just
> creating new device also causes a reprobe, but I can not find any
> evidence now.

This still needs to be described in the commit message.

Only a successful probe should trigger a reprobe, and when the child
devices are registered the parent is not yet on the deferred probe list.
So something is not right or missing here.

Johan