Re: [PATCH v12 1/1] serial: core: Start managing serial controllers to enable runtime PM

[Chen-Yu Tsai]

On Fri, Jun 2, 2023 at 6:13 PM John Ogness <john.ogness@xxxxxxxxxxxxx> wrote:
>
> On 2023-06-02, Chen-Yu Tsai <wenst@xxxxxxxxxxxx> 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