“Of_serial: probe of ff290000.serial failed with error -28” during boot when using 3 UARTs (2 HPS UARTs 1 Altera UART 16550)? - “Of_serial: probe of ff290000.serial failed with error -28” during boot when using 3 UARTs (2 HPS UARTs 1 Altera UART 16550)? Description There is similar error message “Of_serial: probe of ff290000.serial failed with error -28” when using 3 UARTs (2 HPS UARTs 1 Altera UART 16550) or more without modify the Linux kernel configuration default parameter of “ (2)Maximum number of 8250/16550 serial ports”. Resolution You can modify the default parameter of the “Maximum numberof 8250/16550 serial ports” through menuconfig> Device Drivers >Character devices > Serial drivers->(3) Maximum number of 8250/16550 serial ports or other options to match the port number in the design. Custom Fields values: ['novalue'] Troubleshooting FB: 515699; False ['16550 Compatible UART IP'] ['FPGA Dev Tools Quartus® Prime Software Pro'] 16.0 16.0 ['Programmable Logic Devices'] ['novalue'] ['novalue'] ['novalue']