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From:   Doug Anderson <dianders@chromium.org>
Date:   Thu, 18 Aug 2022 16:30:47 -0700
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Subject: Re: [PATCH v1 0/3] Bring back driver_deferred_probe_check_state() for now
To:     Luca Weiss <luca.weiss@fairphone.com>
Cc:     Saravana Kannan <saravanak@google.com>,
        Tony Lindgren <tony@atomide.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Kevin Hilman <khilman@kernel.org>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        Pavel Machek <pavel@ucw.cz>, Len Brown <len.brown@intel.com>,
        Andrew Lunn <andrew@lunn.ch>,
        Heiner Kallweit <hkallweit1@gmail.com>,
        Russell King <linux@armlinux.org.uk>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Naresh Kamboju <naresh.kamboju@linaro.org>,
        kernel-team@android.com, LKML <linux-kernel@vger.kernel.org>,
        Linux PM <linux-pm@vger.kernel.org>,
        netdev <netdev@vger.kernel.org>
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Hi,

On Tue, Aug 16, 2022 at 6:31 AM Luca Weiss <luca.weiss@fairphone.com> wrote:
>
> Hi Saravana,
>
> On Tue Aug 16, 2022 at 1:36 AM CEST, Saravana Kannan wrote:
> > On Mon, Aug 15, 2022 at 9:57 AM Luca Weiss <luca.weiss@fairphone.com> wrote:
> > >
> > > On Mon Aug 15, 2022 at 1:01 PM CEST, Tony Lindgren wrote:
> > > > * Saravana Kannan <saravanak@google.com> [700101 02:00]:
> > > > > More fixes/changes are needed before driver_deferred_probe_check_state()
> > > > > can be deleted. So, bring it back for now.
> > > > >
> > > > > Greg,
> > > > >
> > > > > Can we get this into 5.19? If not, it might not be worth picking up this
> > > > > series. I could just do the other/more fixes in time for 5.20.
> > > >
> > > > Yes please pick this as fixes for v6.0-rc series, it fixes booting for
> > > > me. I've replied with fixes tags for the two patches that were causing
> > > > regressions for me.
> > > >
> > >
> > > Hi,
> > >
> > > for me Patch 1+3 fix display probe on Qualcomm SM6350 (although display
> > > for this SoC isn't upstream yet, there are lots of other SoCs with very
> > > similar setup).
> > >
> > > Probe for DPU silently fails, with CONFIG_DEBUG_DRIVER=y we get this:
> > >
> > > msm-mdss ae00000.mdss: __genpd_dev_pm_attach() failed to find PM domain: -2
> > >
> > > While I'm not familiar with the specifics of fw_devlink, the dtsi has
> > > power-domains = <&dispcc MDSS_GDSC> for this node but it doesn't pick
> > > that up for some reason.
> > >
> > > We can also see that a bit later dispcc finally probes.
> >
> > Luca,
> >
> > Can you test with this series instead and see if it fixes this issue?
> > https://lore.kernel.org/lkml/20220810060040.321697-1-saravanak@google.com/
> >
>
> Unfortunately it doesn't seem to work with the 9 patches

I also tried with the 9 patches, plus an extra fix that Saravana
provided. They didn't fix my use case either. Do we want to land the
reverts as a stopgap so that people aren't broken?

For reference, the device tree for the device I'm testing on is
`arch/arm64/boot/dts/qcom/sc7180-trogdor-lazor-r3-lte.dts`. The device
that's not probing is the bridge chip, AKA 2-002d. Presumably
something about the bridge chip cycles is confusing things since the
remote endpoint that sn65dsi86 needs is actually a child of sn65dsi86
(the panel).

-Doug