Date: Thu, 23 Nov 2023 20:37:26 +0100 From: FreeBSD User <freebsd@walstatt-de.de> To: FreeBSD CURRENT <freebsd-current@freebsd.org> Subject: uSB: uslcom: CP2102 weirdness when serial communication via cu/tip/cutecom Message-ID: <20231123203753.6ca93cc8@thor.intern.walstatt.dynvpn.de>
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Hello, I'm facing some strange behaviour when connecting to a CP2102 USB-UART bridge built-in into a I2C-USB device (I2C is handled by an Amtel88, USB-UART is handled by an CP2102, see here: https://de.elv.com/pc-usb-i2c-interface-200958 for an sketch/overview. The device is recognised as uslcom0 on uhub6 uslcom0: <ELV USB-I2C-Interface> on usbus0 for more details via usbconfig see below. Using FreeBSD CURRENT and 14-STABLE (both most recent) connecting to the device via cu -l /dev/cuaUX -s 115200 results in most cases in a stuck connection. The LED of the device is responding to every keystroke made in the terminal, but I never see any output (which should). In some rare cases disconneting and reconnecting the USB link and connecting via "cu" gives the opportunity for a couple of seconds to enter "?" in the terminal which provides some firmware data on the device - then the communications goes dark. This behaviour is erratic and non predictable. I tried several platforms (hardware), all USB 3, tried FreeBSD 14-STABLE and CURRENT. On a notebook (Lenovo T560) running 14-STABLE the very same situation, but trying the Lenovo with Xubuntu 23.10 gives me a working "cu" and I'm able reading environmental data from the device. Using the methusalem USB 2 port of a computer were available gives me a few seconds more on FreeBSD, before the serial connection goes mute. In cases were possible I tried the same hardware with FreeBSD and Linux Xubuntu, FreeBSD fails, Xubuntu prevails the task. At this point I was quite sure that FreeBSD's uslcom-driver might be the culprit. Out of couriosity I tried a FSBD-13.2RELENG image for AARCH64 (PINE64 I have at hand) and connected the same way, the same device acts as normal as I see under Linux Xubuntu. I'm able to take environmental data as long as I please without a problem so far. Can someone hint me how to debug such a situation? I'm unwilling to use Linux since our infrastructure is based on FreeBSD and ... well, no further explanation on that subject ;-) Thanks in advance, O. Hartmann -- O. Hartmann
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