make flash doesn't preserve serial port settings

[nkolban]

When I execute make flash to flash an ESP32, I find that the serial port settings to my ESP32 aren't preserved after the flash completes. Here is a listing of the settings before a flash:

$ stty -F /dev/ttyUSB0 -a
speed 115200 baud; rows 0; columns 0; line = 0;
intr = ^C; quit = ^\; erase = ^?; kill = ^H; eof = ^D; eol = <undef>; eol2 = <undef>; swtch = <undef>; start = ^Q; stop = ^S; susp = ^Z;
rprnt = ^R; werase = ^W; lnext = ^V; discard = ^O; min = 100; time = 2;
-parenb -parodd -cmspar cs8 -hupcl -cstopb cread clocal -crtscts
-ignbrk brkint ignpar -parmrk -inpck -istrip -inlcr -igncr -icrnl ixon -ixoff -iuclc -ixany -imaxbel -iutf8
-opost -olcuc -ocrnl -onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0 ff0
-isig -icanon iexten -echo echoe echok -echonl -noflsh -xcase -tostop -echoprt echoctl echoke -flusho -extproc

and the same settings after executing a make flash:

$ stty -F /dev/ttyUSB0 -a
speed 921600 baud; rows 0; columns 0; line = 0;
intr = ^C; quit = ^\; erase = ^?; kill = ^H; eof = ^D; eol = <undef>; eol2 = <undef>; swtch = <undef>; start = ^Q; stop = ^S; susp = ^Z;
rprnt = ^R; werase = ^W; lnext = ^V; discard = ^O; min = 0; time = 0;
-parenb -parodd -cmspar cs8 -hupcl -cstopb cread clocal -crtscts
-ignbrk brkint ignpar -parmrk -inpck -istrip -inlcr -igncr -icrnl -ixon -ixoff -iuclc -ixany -imaxbel -iutf8
-opost -olcuc -ocrnl -onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0 ff0
-isig -icanon -iexten -echo -echoe -echok -echonl -noflsh -xcase -tostop -echoprt -echoctl -echoke -flusho -extproc

I would have expected the settings to have been preserved.

[negativekelvin]

Doesn't the port keep the settings from the last program that used/configured it? Which would be esptool.py

[nkolban]

I guess what I am then querying is the semantics that using esptool.py changes the existent settings of the serial port without restoring them to their original values at termination. If we wish to define that the semantics of the serial port are "undefined" at the end of a run of esptool.py then that would be fine ... we just need clarity on what to expect ... and my un-considered expectations are that the serial port would have the same settings after running a utility as before.

[negativekelvin]

Seems like more times than not it would be preferred that the settings stay the same as when the port was last used. Is there any precedent that a program stores and reverts the port settings? It's not something I would expect.

[projectgus]

It seems reasonable we should restore the original serial port settings on exit. This would probably be better opened as an issue against github.com/themadinventor/esptool, but I can track it from here.

[projectgus]

Moved to an esptool feature request.