Send an USB remote wakeup if data need to be written #5135
Conversation
On Linux, setting autosuspend_delay_ms to N and control to auto allows the host pc to suspend the peripheral. Some Linux distro (Ubuntu, Mint) apply this behaviour by default. If the sketch's prints where less frequent than N milliseconds the sketch prints would never arrive. This patch allows sending a remote wakeup event to unsuspend the peripheral and allow the serial prints to be received.
|
This sounds like it has been a fun debugging session, but I guess it's a good thing to fix (can't really comment on the implementation, though). Is a similar fix needed for the 16u2 on the Uno and similar? |
|
✅ Build completed. Please test this code using one of the following: ⬇️ http://downloads.arduino.cc/javaide/pull_requests/arduino-PR-5135-BUILD-575-linux32.tar.xz ℹ️ The |
|
Quite funny debug session indeed 😄 On 16u2 it shouldn't be necessary, the OS should never suspend a peripheral if it doesn't expose the The kernel never applies the autosuspend policy automatically (from https://www.kernel.org/doc/Documentation/usb/power-management.txt This means that non-hub devices won't be autosuspended unless the user or a program explicitly enables it ). In any case, we know how to handle it now 😉 |
|
Have you tried compiling it for the u2 series? If this function is useless, you could add a #define around it, so we don't use an additional overhead for the small flash we have. |
|
Hi Nico, I didn't test on 16u2 using the AVR core but I believe it should behave like the 32u4 (so the fix is needed). My answer was about stock 16u2 firmware on UNO (which doesn't expose as |
|
Looks like the 16u2 should support this from the datasheet. |
Yes, but AFAIU the regular USB-to-serial 16u2 firmware does not advertise support, so there is no problem. The Arduino core intended for the |
|
There is not a single board available with a 16u4, so I do not understand what you are trying to point out. |
|
Uh, that should have read 32u4. I mean the Arduino core that runs on e.g. the Leonardo. |
On Linux, setting autosuspend_delay_ms to N and control to auto allows the host pc to suspend the peripheral. Some Linux distro (Ubuntu, Mint) apply this behaviour by default.
If the sketch's prints where less frequent than N milliseconds the sketch prints would never arrive.
This patch allows sending a remote wakeup event to unsuspend the peripheral and allow the serial prints to be received.