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Subject: Re: [PATCH 1/2] tty: serial: qcom_geni_serial: No need to stop tx/rx on UART shutdown
From:   Stephen Boyd <swboyd@chromium.org>
Cc:     mka@chromium.org, ryandcase@chromium.org,
        bjorn.andersson@linaro.org, akashast@codeaurora.org,
        skakit@codeaurora.org, rojay@codeaurora.org,
        mgautam@codeaurora.org, Douglas Anderson <dianders@chromium.org>,
        Andy Gross <agross@kernel.org>,
        Doug Anderson <dianders@google.com>,
        Girish Mahadevan <girishm@codeaurora.org>,
        Jiri Slaby <jslaby@suse.com>,
        Karthikeyan Ramasubramanian <kramasub@codeaurora.org>,
        Sagar Dharia <sdharia@codeaurora.org>,
        linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-serial@vger.kernel.org
To:     Douglas Anderson <dianders@chromium.org>,
        gregkh@linuxfoundation.org
Date:   Mon, 16 Mar 2020 10:57:35 -0700
Message-ID: <158438145518.88485.3909168358047756949@swboyd.mtv.corp.google.com>
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Quoting Douglas Anderson (2020-03-13 13:46:51)
> On a board using qcom_geni_serial I found that I could no longer
> interact with kdb if I got a crash after the "agetty" running on the
> same serial port was killed.  This meant that various classes of
> crashes that happened at reboot time were undebuggable.
>=20
> Reading through the code, I couldn't figure out why qcom_geni_serial
> felt the need to run so much code at port shutdown time.  All we need
> to do is disable the interrupt.
>=20
> After I make this change then a hardcoded kgdb_breakpoint in some late
> shutdown code now allows me to interact with the debugger.  I also
> could freely close / re-open the port without problems.
>=20
> Fixes: c4f528795d1a ("tty: serial: msm_geni_serial: Add serial driver sup=
port for GENI based QUP")
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> ---

Matches what is described in Documentation/driver-api/serial/driver.rst

Reviewed-by: Stephen Boyd <swboyd@chromium.org>