feat(esptool): Add --retry-open-serial flag, config file entry and envar (ESPTOOL-890)

[2opremio]

esptool frequently fails when trying to open the serial port of a device which deep-sleeps often:

$ esptool.py --chip esp32s3 -p /dev/cu.usbmodem6101 [...] write_flash foo.bin Serial port /dev/cu.usbmodem6101

A fatal error occurred: Could not open /dev/cu.usbmodem6101, the port is busy or doesn't exist.
([Errno 35] Could not exclusively lock port [...]: [Errno 35] Resource temporarily unavailable)

This makes developers add unnecessarily long sleepswhen the main CPU is awake, in order to give esptool the chance to find the serial port.

This PR adds a new flag --retry-open-serial (with corresponding env variable and cfg file entry) which retries opening the port indefinitely until the device shows up:

$ esptool.py --chip esp32s3 -p /dev/cu.usbmodem6101 [...] write_flash --retry-open-serial foo.bin Serial port /dev/cu.usbmodem6101
[Errno 35] Could not exclusively lock port [...]: [Errno 35] Resource temporarily unavailable Retrying to open port .........................
Connecting....
Chip is ESP32-S3 (QFN56) (revision v0.2)
[...]

I have tested this change with the following hardware & software combinations:

ESP32S3 + esptool master branch

I have run the esptool.py automated integration tests with this change and the above hardware:

"NO TESTING" (I can do so if considered necessary in order to merge)

I did test the flag, the env variable and the config file entry though.

[2opremio]

This is a counterpart to https://github.com/espressif/esp-idf-monitor/pull/15

[2opremio]

CC @sudeep-mohanty who I am sure will appreciate the feaure when developing ULP code :)

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[sudeep-mohanty]

CC @sudeep-mohanty who I am sure will appreciate the feaure when developing ULP code :)

Thanks for the contribution @2opremio! Seems like a useful feature! But, I'd let our colleagues from the esptool team to further evaluate the changes. Thanks! :)

[2opremio]

I am not sure I understand the linux-arm32 error on CI but it seems it's also failing in master

[2opremio]

I am away this week, so, feel free to address the comments yourselves. Otherwise I will do so next week once I am back.

On August 5, 2024, GitHub @.***> wrote:

@peterdragun commented on this pull request.

Hi, first of all, thank you for your contribution, and I am sorry for the late response.

We have discussed this with the team and we think that this would be a nice addition to esptool. Overall we like the feature, but I have left some comments regarding the implementation.

Please let me know if you want to address them, if not we will do it by ourselves.

Thank you!

In docs/en/esptool/configuration-file.rst https://github.com/espressif/esptool/pull/995#discussion_r1703926561:

@@ -109,6 +109,8 @@ Complete list configurable options: +------------------------------ +----------------------------------------------------------- +----------+ | custom_reset_sequence | Custom reset sequence for resetting into the bootloader | | +------------------------------ +----------------------------------------------------------- +----------+ +| retry_open_serial | Retry opening the serial port indefinitely | False | Please fix the indentation to match the rest of the table

In esptool/init.py https://github.com/espressif/esptool/pull/995#discussion_r1703930400:

• parser.add_argument( + "--retry-open-serial", + help=( + "Retry opening the serial port indefinitely. " + "Default: %s" % DEFAULT_RETRY_OPEN_SERIAL + ), + default=os.environ.get("ESPTOOL_RETRY_OPEN_SERIAL", DEFAULT_RETRY_OPEN_SERIAL), + action="store_true", + ) We are trying to keep the number of arguments for esptool as slim as possible. It should be sufficient to configure this function using ENV and config variables.

In esptool/init.py https://github.com/espressif/esptool/pull/995#discussion_r1703938427:

• _esp = get_default_specific_connected_device( + chip, + each_port,
• initial_baud, + trace, + before, + connect_attempts, + retry_open_serial, + ) I think it only makes sense to run the retry open if the user has specified the port. In this case, it will also trigger on the auto- detected port.

In esptool/init.py https://github.com/espressif/esptool/pull/995#discussion_r1703939222:

• ) as e: + if not retry_open_serial: + raise + if _esp and _esp._port: + _esp._port.close() + _esp = None + if retry_attempts == 0: + print(e) + print("Retrying failed connection ", end="", flush=True) + else: + if retry_attempts % 9 == 0: + # print a dot every second + print(".", end="", flush=True) + time.sleep(0.1) + retry_attempts += 1 + continue this continue is not necessary

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[2opremio]

@peterdragun PTAL.

I've rebased the pre-existing code into a single commit and addressed all the comments (into a separate commit to differentiate it).