Enable remote_bitbang by default on next release? (OCD-696)

[brainstorm]

Hello Espressif,

I'm connecting to the ESP32S2 using the newly released "Glasgow" explorer board:

https://www.crowdsupply.com/1bitsquared/glasgow

Which supports that remote_bitbang probe interfacing via a so-called FPGA "applet":

$ glasgow run jtag-openocd --pin-tck 0 --pin-tms 3 --pin-tdi 2 --pin-tdo 1 -V 3.3 tcp:localhost:2222
I: g.device.hardware: building bitstream ID b97acf8ca32a08beb46d6713ecdb8b98
Warning: Wire top.$flatten\i2c_target.\bus.$verilog_initial_trigger has an unprocessed 'init' attribute.
Warning: Wire top.$flatten\multiplexer.\U$$0.\U$$2.$verilog_initial_trigger has an unprocessed 'init' attribute.
Warning: Wire top.$flatten\multiplexer.\U$$0.\U$$2.\bus.$verilog_initial_trigger has an unprocessed 'init' attribute.
Warning: Wire top.$verilog_initial_trigger has an unprocessed 'init' attribute.
I: g.cli: running handler for applet 'jtag-openocd'
I: g.applet.interface.jtag_openocd: port(s) A, B voltage set to 3.3 V
I: g.applet.interface.jtag_openocd: socket: listening at tcp:localhost:2222

Unfortunately, to my surprise, I found that remote_bitbang is disabled by default on my OpenOCD-ESP32 build?

$ which openocd
/Users/romanvg/.espressif/tools/openocd-esp32/v0.10.0-esp32-20200709/openocd-esp32/bin/openocd
$ openocd --version
Open On-Chip Debugger  v0.10.0-esp32-20200709 (2020-07-09-08:54)
Licensed under GNU GPL v2

$ openocd -c 'interface remote_bitbang; remote_bitbang_port 2222'
Open On-Chip Debugger  v0.10.0-esp32-20200709 (2020-07-09-08:54)
Licensed under GNU GPL v2
For bug reports, read
        http://openocd.org/doc/doxygen/bugs.html
Error: The specified debug interface was not found (remote_bitbang)
The following debug interfaces are available:
1: ftdi
2: usb_blaster
3: ft232r
4: jlink
5: vsllink
6: ulink
7: hla
8: osbdm
9: opendous
10: aice
11: xds110

Could you please enable it back on future builds? Thanks in advance!

[brainstorm]

OTOH, enabling BUILD_REMOTE_BITBANG 1 from a master clone still fails:

$ ./openocd -c 'interface remote_bitbang; remote_bitbang_port 2222'
Open On-Chip Debugger  v0.10.0-esp32-20201202 (2021-01-02-21:22)
Licensed under GNU GPL v2
For bug reports, read
	http://openocd.org/doc/doxygen/bugs.html
Error: The specified debug interface was not found (remote_bitbang)
The following debug interfaces are available:
1: ftdi
2: usb_blaster
3: esp_usb_jtag
4: esp_usb_jtag
5: ft232r
6: presto
7: usbprog
8: openjtag
9: jlink
10: vsllink
11: rlink
12: ulink
13: arm-jtag-ew
14: hla
15: osbdm
16: opendous
17: aice
18: cmsis-dap
19: kitprog
20: xds110
21: jtag_esp_remote

But there's the last jtag_esp_remote which seems to have been implemented just a few months ago... are there any official docs on how to use that new interface? What was the reasoning behind not having the generic remote_bitbang?

OffTopic: Two duplicated esp_usb_jtag on indices 3&4? What is the difference between them?

[brainstorm]

Navigating the jtag_esp_remote commit referred above and its sample .cfg file...

$ ./src/openocd -c 'interface jtag_esp_remote; set protocol tcp; jtag_esp_remote_set_port tcp:2222; jtag_esp_remote_set_address "127.0.0.1"'
Open On-Chip Debugger  v0.10.0-esp32-20201202 (2021-01-02-21:22)
Licensed under GNU GPL v2
For bug reports, read
	http://openocd.org/doc/doxygen/bugs.html
Info : only one transport option; autoselect 'jtag'
Error: TCP protocol must be set up for jtag_esp_remote_set_port

[brainstorm]

Finally, after adding jtag_esp_remote_protocol tcp:

$ ./src/openocd -c 'interface jtag_esp_remote; jtag_esp_remote_protocol tcp; jtag_esp_remote_set_port 2222; jtag_esp_remote_set_address "127.0.0.1"'
Open On-Chip Debugger  v0.10.0-esp32-20201202 (2021-01-02-21:22)
Licensed under GNU GPL v2
For bug reports, read
	http://openocd.org/doc/doxygen/bugs.html
Info : only one transport option; autoselect 'jtag'
Info : TCP protocol set for esp remote
Info : Set server port to 2222
Info : Set server address to 127.0.0.1
Info : Listening on port 6666 for tcl connections
Info : Listening on port 4444 for telnet connections
Info : Connection to 127.0.0.1 : 2222 succeed
Info : This adapter doesn't support configurable speed
Warn : There are no enabled taps.  AUTO PROBING MIGHT NOT WORK!!

[igrr]

@brainstorm jtag_esp_remote is a different protocol from remote_bitbang, so as you have probably already realized, it won't work with tools that implement remote_bitbang. So far, we don't have devices which natively support jtag_esp_remote protocol released publicly, it is added as a provision for future devices.
Can definitely enable remote_bitbang protocol in the next release.

[brainstorm]

Yes, figured, thanks Igor, I'll fix up the PR tonight, very easy fix ;)

[brainstorm]

@erhankur ... so, was it solved elsewhere or will the PR be merged?

[erhankur]

@brainstorm Sorry, I missed adding a closing comment. Yes, we built with --enable-remote-bitbang option in the latest release.