e remains zero and in the end the FCR register is set to zero which results in disabled FIFOs even if the UART type is 16550A. This is also true for other types of UARTs with FIFOs. If the UART is autoconfigured via 'setserial /dev/ttySx autoconfig' then port.fifosize and tx_loadsz are initialized correctly in the autoconfig() function and the UART is working correctly then. I checked the source codes and I can say that this bug is present in 2.6.x series of kernels for a couple of years. Namely I can confirm its presence in 2.6.16.57, 2.6.32.24 and 2.6.36.1 (tested all of them on our hardware). I think it was not noticed before because not many people use manually configured non PNP UARTs on ISA/LPC bus these days. Also the data loss caused by buffer overruns occures only if IRQ latency is higher then time needed to receive one character on given communication speed. For example our hardware looses received characters only if the UARTs are connected throught LPC bus with SERIRQ (serial IRQ transport) and not if they are connected to ISA bus because LPC SERIRQ has higher interrupt latency then parallel ISA interupt lines. Here is the patch to correct the bug created against 2.6.36.1: Signed-off-by: Ondrej Puzman Signed-off-by: Greg Kroah-Hartman nI[›’%x