Hi, A recent change has added a SERIAL_8250_16550A_VARIANTS option, which lets one request the 8250 driver not to probe for 16550A device features so as to reduce the driver's device startup time in virtual machines. This has turned out problematic to a more recent update for the OxSemi Tornado series PCIe devices, whose new baud rate generator handling code actually requires switching hardware into the enhanced mode for correct operation, which actually requires 16550A device features to have been probed for. This small patch series fixes the issue by letting individual device subdrivers to request full 16550A device feature probing by means of a flag regardless of the SERIAL_8250_16550A_VARIANTS setting chosen. The changes have been verified with an OXPCIe952 device, in the native UART mode and a 64-bit RISC-V system as well as in the legacy UART mode and a 32-bit x86 system. Credit to Anders for reporting this issue and then working through the resolution. Maciej
