The RevPi kernel has been updated from version 5.10 to 6.1 and is thus up to par again with the version used by RaspberryPi OS. It is based on version 6.1.46 of the stable kernel and version 6.1.46-rt13 of the real-time kernel patches. Beside general bug fixes and improvements in drivers and subsystems, the following has changed:
piControl:
The piControl kernel module has been largely reworked: A significant portion of it has been moved to an in-kernel driver that registers a "serdev" device and handles all RS-485 communication on the PiBridge. This gets us one step closer to our long-term goal of upstreaming piControl into the mainline kernel.
The driver is compiled into the RevPi kernel, so as before only the piControl module needs to be loaded to communicate with the RevPi devices. When building your own kernel from our kernel source repository, the driver can optionally be built as an independent kernel module "pibridge.ko". For this the configuration parameter CONFIG_SERIAL_DEV_MUX_PIBRIDGE must be changed from 'y' to 'm' in the kernel configuration. When using the pibridge driver as a standalone kernel module, it must be loaded before loading the piControl module.
One result of the reworked architecture is that latency for the communication with connected RevPi modules has decreased, so that now shorter cycle times are achieved when querying and setting device state.
TPM:
The TPM interrupt is now supported, so the processor load is reduced when using the TPM. In addition, it is now ensured that the TPM chip is correctly taken out of reset during booting and thus correctly recognized when loading the driver.
RTC:
The timestamping feature has been deactivated for the PCF2127. This works around a hardware erratum where a bit in one of the RTC interrupt registers was set by mistake during a warm restart. The erroneous set bit led to a malfunction of the watchdog on the Connect 4.