linux-kernel - [PATCH 0/3] serial: qcom-geni: fix lockups

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Message-ID: <20240624133135.7445-1-johan+linaro@kernel.org>
Date: Mon, 24 Jun 2024 15:31:32 +0200
From: Johan Hovold <johan+linaro@...nel.org>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jirislaby@...nel.org>
Cc: Konrad Dybcio <konrad.dybcio@...aro.org>,
	Douglas Anderson <dianders@...omium.org>,
	Bjorn Andersson <andersson@...nel.org>,
	linux-arm-msm@...r.kernel.org,
	linux-serial@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Johan Hovold <johan+linaro@...nel.org>
Subject: [PATCH 0/3] serial: qcom-geni: fix lockups

Since 6.10-rc1, Qualcomm machines with a serial port can easily lock up
hard, for example, when stopping a getty on reboot.

The first patch in this series fixes this severe regression by restoring
the pre-6.10-rc1 behaviour of printing additional characters when
flushing the tx buffer.

The second patch fixes a long-standing issue in the GENI driver which
can lead to a soft lock up when using software flow control and on
suspend.

The third patch, addresses the old issue with additional characters
being printing when flushing the buffer.

Note that timeouts used when clearing the tx fifo are a bit excessive
since I'm reusing the current qcom_geni_serial_poll_bit() helper for
now.

I think at least the first patch should be merged for rc6 while we
consider the best way forward to address the remaining issues.

Doug has posted an alternative series of fixes here that depends on
reworking the driver a fair bit here:

	https://lore.kernel.org/lkml/20240610222515.3023730-1-dianders@chromium.org/

Johan

Johan Hovold (3):
  serial: qcom-geni: fix hard lockup on buffer flush
  serial: qcom-geni: fix soft lockup on sw flow control and suspend
  serial: qcom-geni: fix garbage output after buffer flush

 drivers/tty/serial/qcom_geni_serial.c | 36 +++++++++++++++++++--------
 1 file changed, 25 insertions(+), 11 deletions(-)

-- 
2.44.1