Message-ID: <5716BDF1.1010407@gmail.com>
Date: Tue, 19 Apr 2016 16:23:29 -0700
From: Frank Rowand <frowand.list@gmail.com>
Reply-To: frowand.list@gmail.com
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To: ivan.ivanov@linaro.org
CC: agross@codeaurora.org, David Brown <davidb@codeaurora.org>,
        srinivas.kandagatla@linaro.org,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>, jslaby@suse.com,
        Rob Herring <robh+dt@kernel.org>, Pawel Moll <pawel.moll@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Ian Campbell <ijc+devicetree@hellion.org.uk>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        Linux Kernel list <linux-kernel@vger.kernel.org>,
        "linux-arm-msm@vger.kernel.org" <linux-arm-msm@vger.kernel.org>,
        linux-soc@vger.kernel.org, linux-serial@vger.kernel.org
Subject: regression: 3a878c430fd6 ("tty: serial: msm: Add TX DMA support")
 drops data
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Hi Ivan,

It appears that I have found a regression caused by
3a878c430fd6 ("tty: serial: msm: Add TX DMA support").

When I cat a file slightly larger than 126000 bytes on
the console, viewed via minicom connected to the serial
port, I am losing random chunks of data, almost always
three bytes in length.  I have also seen a lost chunk
of two bytes.

I am using the 8074 dragonboard, with the dts of
arch/arm/boot/dts/qcom-apq8074-dragonboard.dts.
The dts node is serial@f991e000, which has a
compatible of "qcom,msm-uartdm-v1.4", so is_uartdm
should be UARTDM_1P4.

Do you have any thoughts on what might be going
wrong, or what I can do to debug this?

Thanks,

Frank