linux-kernel - [PATCH v2 0/1] gpio: add simple logic analyzer using polling

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Date:   Sat, 18 Sep 2021 10:33:06 +0200
From:   Wolfram Sang <wsa+renesas@...g-engineering.com>
To:     linux-gpio@...r.kernel.org
Cc:     linux-renesas-soc@...r.kernel.org,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        linux-kernel@...r.kernel.org,
        Wolfram Sang <wsa+renesas@...g-engineering.com>
Subject: [PATCH v2 0/1] gpio: add simple logic analyzer using polling

The bravery continues with the next update of the in-kernel logic
analyzer based on GPIO polling with local irqs disabled. It has been
been tested locally and remotely. It provided satisfactory results.
Besides the driver, there is also a script which isolates a CPU to
achieve the best possible result. I am aware of the latency limitations.
However, the intention is for debugging only, not mass production.
Especially for remote debugging and to get a first impression, this has
already been useful. Documentation is within the patch, to get a better
idea what this is all about.

Changes since v1:

* addressed Andy's review comments (thanks!)
  * mutex gets destroyed on remove
  * make use of the snprintf return value
  * improved errno
  * script: use only progname instead of $0
  * script: refactor 'shift' usage in command line handling
  * spelling fixes
* script: fixed a bug when using '--instance'
* short success message after proper initialization

I had a look at Andy's other suggestion, too, but decided against them.
Either I liked the current style better or they can be added later when
we actually need them.

I've used the analyzer in a few more scenarios and was happy with the
outcome. Looking forward to other tests and comments. From my side this
looks good to go.

Happy hacking,

   Wolfram

Wolfram Sang (1):
  gpio: add sloppy logic analyzer using polling

 .../dev-tools/gpio-sloppy-logic-analyzer.rst  |  71 ++++
 Documentation/dev-tools/index.rst             |   1 +
 drivers/gpio/Kconfig                          |  17 +
 drivers/gpio/Makefile                         |   1 +
 drivers/gpio/gpio-sloppy-logic-analyzer.c     | 341 ++++++++++++++++++
 tools/gpio/gpio-sloppy-logic-analyzer         | 221 ++++++++++++
 6 files changed, 652 insertions(+)
 create mode 100644 Documentation/dev-tools/gpio-sloppy-logic-analyzer.rst
 create mode 100644 drivers/gpio/gpio-sloppy-logic-analyzer.c
 create mode 100755 tools/gpio/gpio-sloppy-logic-analyzer

-- 
2.30.2