linux-kernel - Re: [PATCH] Revert "of: property: fw_devlink: Add support for remote-endpoint"

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Date:   Tue, 5 Oct 2021 17:21:19 -0700
From:   Saravana Kannan <saravanak@...gle.com>
To:     Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Stephen Boyd <sboyd@...nel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>
Subject: Re: [PATCH] Revert "of: property: fw_devlink: Add support for remote-endpoint"

On Fri, Oct 1, 2021 at 6:04 PM Dmitry Baryshkov
<dmitry.baryshkov@...aro.org> wrote:
>
> On 28/09/2021 04:13, Saravana Kannan wrote:
> > On Mon, Sep 27, 2021 at 5:56 PM Dmitry Baryshkov

<snip>

> >> After doing the analysis, I can confirm that I was too quick regarding
> >> the mdss links preventing it from being probed. Sorry about that.
> >>
> >> It all went up to the DP phy having a link with usb-c-connector. I was
> >> running the kernel 5.15-rc1, so your tcpm fix is already present.
> >> However my colleague has disabled the tcpm device (which I did not
> >> notice). So the driver did not call fw_devlink_purge_absent_suppliers().
> >> The devlink still exists:
> >
> > Let me take a closer look at this before the end of this week. Can you
> > point me to the exact DT changes that were made that's causing this
> > issue? It should help me debug the issue. I have a guess on what the
> > issue might be.
>
> Here is the kernel source:
> https://git.linaro.org/people/bryan.odonoghue/kernel.git/log/?h=5.15-rc1-camss-v2
>
> The change that causes PHY driver to silently stop probing, causing an
> avalanche of devices not being probed:
>
> https://git.linaro.org/people/bryan.odonoghue/kernel.git/commit/?h=5.15-rc1-camss-v2&id=d0bf3fc47c132968c302965154eeb5c88007fa73

Sorry, I haven't had a chance to look into this yet, but I still have
a strong hunch that this is related to how of_device_is_available()
doesn't recurse up till the root to check if a node is disabled (if a
parent is disabled, the child should also be considered disabled). And
I think patch series should help your case due to a side effect (it
wasn't meant as a fix for your issue). Can you give it a shot?

https://lore.kernel.org/lkml/20210929000735.585237-1-saravanak@google.com/

-Saravana