Interfacing (DSI, CSI, I2C, etc.) • Re: RPi Zero 2 W, UART w/ CTS, ready to give up

Looking at the kernel driver, the pl011 driver appears not to support the CRTSCTS flag for automatic flow control in hardware

Oh yes it does: https://github.com/raspberrypi/linux/bl ... 11.c#L1653

Isn't that just the manual RTS (TIOCM_RTS) output handling? Documented in https://www.man7.org/linux/man-pages/ma ... ctl.4.html

Automatic flow control is via CRTSCTS (https://www.man7.org/linux/man-pages/ma ... ios.3.html), which pl011 responds to by setting port->status bit UPSTAT_AUTORTS. serial-core then sets/clears RTS from uart_throttle / uart_unthrottle.

Whilst there is also an UPSTAT_AUTOCTS flag defined, I don't actually see any code doing anything with it.

Statistics: Posted by 6by9 — Thu Apr 25, 2024 5:49 pm

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