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From:   Heiko Thiery <heiko.thiery@gmail.com>
Date:   Mon, 20 Sep 2021 11:17:46 +0200
Message-ID: <CAEyMn7bN247-J=Qz-k3LZMVYb8pdYSP3BSCsNE9yyvfDfmdK0g@mail.gmail.com>
Subject: Re: imx8mm board crash in drivers/usb/chipidea/ci_hdrc_imx.c
To:     Fabio Estevam <festevam@gmail.com>
Cc:     Peter Chen <peter.chen@nxp.com>, Jun Li <jun.li@nxp.com>,
        Yu Kuai <yukuai3@huawei.com>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Mark Brown <broonie@kernel.org>,
        USB list <linux-usb@vger.kernel.org>,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@lists.infradead.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Shawn Guo <shawnguo@kernel.org>,
        Frieder Schrempf <frieder.schrempf@kontron.de>
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Hi Fabio,

Am So., 19. Sept. 2021 um 23:44 Uhr schrieb Fabio Estevam <festevam@gmail.com>:
>
> Hi Heiko,
>
> On Sun, Sep 19, 2021 at 4:33 PM Heiko Thiery <heiko.thiery@gmail.com> wrote:
>
> > > Does this patch help?
> > > https://pastebin.com/raw/yZKz1huL
> >
> > I can confirm that on the next-20210915 (that includes commit
> > 78e80c4b4238c1f5642b975859664fced4f9c69e) your provided patch solves
> > the problem.
>
> Thanks for testing it.
>
> > But is it explainable that in the version before the commit
> > 78e80c4b4238c1f5642b975859664fced4f9c69e the problem occurs in the
> > form I reported?
>
> I don't understand this problem either. I would suggest bisecting it.

Now it is clear to me. I used the dtb for my board that had already
changed the phy node and tried to boot the "old" kernel 5.14. Thus no
phy could be found. Nevertheless the kernel should not crash in case
no phy was found.

So I made a beginner's mistake here. But this also means that you can
no longer start an old kernel with the changed dtb. This comes into
play when you e.g. a standard distribution where the embedded dtb is
passed from the uboot via EFI boot.

-- 
Heiko