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d681a6e4e3
The commite42d6c3ec0("serial: qcom_geni_serial: Make kgdb work even if UART isn't console") worked pretty well and I've been doing a lot of debugging with it. However, recently I typed "dmesg" in kdb and then held the space key down to scroll through the pagination. My device hung. This was repeatable and I found that it was introduced with the aforementioned commit. It turns out that there are some strange boundary cases in geni where in some weird situations it will signal RX_LAST but then will put 0 in RX_LAST_BYTE. This means that the entire last FIFO entry is valid. This weird corner case is handled in qcom_geni_serial_handle_rx() where you can see that we only honor RX_LAST_BYTE if RX_LAST is set _and_ RX_LAST_BYTE is non-zero. If either of these is not true we use BYTES_PER_FIFO_WORD (4) for the size of the last FIFO word. Let's fix kgdb. While at it, also use the proper #define for 4. Fixes:e42d6c3ec0("serial: qcom_geni_serial: Make kgdb work even if UART isn't console") Signed-off-by: Douglas Anderson <dianders@chromium.org> Reviewed-by: Akash Asthana <akashast@codeaurora.org> Link: https://lore.kernel.org/r/20200806221904.1.I4455ff86f0ef5281c2a0cd0a4712db614548a5ca@changeid Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.