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References: <20230525113034.46880-1-tony@atomide.com> <20230602083335.GA181647@google.com>
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From:   Chen-Yu Tsai <wenst@chromium.org>
Date:   Mon, 5 Jun 2023 11:04:28 +0800
Message-ID: <CAGXv+5Gy=SqKukrDTpx+qVDgNDzMmMcC+Y0wkgfRA9xZCKBA6w@mail.gmail.com>
Subject: Re: [PATCH v12 1/1] serial: core: Start managing serial controllers
 to enable runtime PM
To:     John Ogness <john.ogness@linutronix.de>
Cc:     Tony Lindgren <tony@atomide.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jirislaby@kernel.org>,
        Andy Shevchenko <andriy.shevchenko@intel.com>,
        Dhruva Gole <d-gole@ti.com>,
        =?UTF-8?Q?Ilpo_J=C3=A4rvinen?= <ilpo.jarvinen@linux.intel.com>,
        Johan Hovold <johan@kernel.org>,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        linux-omap@vger.kernel.org,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org,
        =?UTF-8?B?TsOtY29sYXMgRi4gUi4gQS4gUHJhZG8=?= 
        <nfraprado@collabora.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        linux-mediatek@lists.infradead.org
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On Fri, Jun 2, 2023 at 6:13=E2=80=AFPM John Ogness <john.ogness@linutronix.=
de> wrote:
>
> On 2023-06-02, Chen-Yu Tsai <wenst@chromium.org> wrote:
> > This patch, in linux-next since 20230601, unfortunately breaks
> > MediaTek based Chromebooks. The kernel hangs during the probe of the
> > serial ports, which use the 8250_mtk driver.
>
> Are you sure it is this patch? Have you bisected it?
>
> Unfortunately next-20230601 also brought in a series that added
> spinlocking to the 8250 driver. That may be the issue here instead.
>
> For 8250 bug reports we really need to bisection.

As Tony mentioned, you're off the hook for it.

I should've been more clear. After reverting the top three patches in
drivers/tty/serial from next-20230602, the system booted correctly again:

    539914240a01 serial: core: Fix probing serial_base_bus devices
    d0a396083e91 serial: core: Don't drop port_mutex in
serial_core_remove_one_port
    84a9582fd203 serial: core: Start managing serial controllers to
enable runtime PM

ChenYu