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From:   Chen-Yu Tsai <wenst@chromium.org>
Date:   Wed, 7 Jun 2023 12:46:51 +0800
Message-ID: <CAGXv+5ERwrFgpWBUBTkoawfyyTHU9w=Owiy-2BbCXHwEpZk1tA@mail.gmail.com>
Subject: Re: [PATCH v12 1/1] serial: core: Start managing serial controllers
 to enable runtime PM
To:     Tony Lindgren <tony@atomide.com>
Cc:     John Ogness <john.ogness@linutronix.de>,
        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 Tue, Jun 6, 2023 at 8:21=E2=80=AFPM Tony Lindgren <tony@atomide.com> wro=
te:
>
> * Chen-Yu Tsai <wenst@chromium.org> [230606 09:17]:
> > I ended up following 8250_dw's design, which seemed less convoluted.
> > The original code was waaay too convoluted.
>
> OK that looks good to me thanks. Good to hear you got it sorted out.
>
> The 8250_dw style runtime PM is a good solution for simple cases. Where
> it won't work are SoCs where runtime PM calls need to propagate up the
> bus hierarchy. For example, 8250_omap needs runtime PM calls for the
> interconnect and power domain to get register access working.

Good to know. On MediaTek platforms I don't think there are any power
domains covering the basic peripherals. (Or it's hidden from the kernel.)

> > BTW, the Bluetooth breakage seems like a different problem.
>
> OK seems like we're good to go then :)

Yup. After a bit more testing, it seems the Bluetooth problem is more like
an undervolt issue. If I have WiFi and BT probe at the same time, Bluetooth
fails. If they probe separately, everything works fine.

ChenYu