Hi all, We're using industrial PCs with a Fintek F81866 UART controller. It claims "high baud rate support" but reports 115200 after boot. After googling it, i found some contributions to the linux kernel from Fintek: https://patchwork.kernel.org/patch/9361345/ They did not implement their own driver, but add some functionality to the standard 8250 serial driver in a separate file "8250_fintek.c". Too bad the author also states "9Bit/High baud rate(not implements with mainline)". After some unsuccessful e-mail traffic with Fintek, I tried implementing it on my own. I found this datasheet: http://pdf1.alldatasheet.com/datasheet-pdf/view/459085/FINTEK/F81866AD-I.html On page 113 it explains which UART clock rate is needed for which actual baud rate. So - as explained on page 179 - I successfully changed register F2h to use 14.769MHz (8 times faster than default 1.84MHz clock) and therefore support baud rates up to 921600. Confirmed it is working... At this point, I could contribute the change and try getting it mainline?! It's basically two lines of code... ----- But now it starts getting tricky. Maybe it's a second step regarding mainline, but I also need to support uncommon baudrates like B500000. According to the baud rate table (page 113) I need to set uart clock even higher (24MHz) in order to get a proper divisor for those baud rates but set it back if a common baud rate is requested. In my opinion, the driver needs to decide which clock rate is perfect for the requested baudrate. I think I need to do this when someone is changing termios. So I found "serial8250_do_set_termios()" function in 8250_port.c. But at this point I'm stuck. I cannot figure out where to put that functionality. As I'm afraid never getting it mainline, if I mess around in serial_core and 8250_core, I wanted to ask you guys for some hints/ideas. Thanks, Lukas -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
