On Thu, 5 Jul 2018 14:39:21 +0800 Jisheng Zhang wrote: <snip>
> > > > > + serial_port_out(p, UART_LCR, up->lcr | UART_LCR_DLAB); > > > + serial_dl_write(up, quot); > > > > At some point it would be a helper, I think. We can call > > serial8250_do_set_divisor() here. So, perhaps we might export it. > > serial8250_do_set_divisor will drop the frac, that's not we want ;) > And most importantly, serial8250_do_set_divisor() will set a wrong BRD(I) for fractional capable DW uarts. For example, clk = 25MHZ, baud = 115200. In fractional capable DW uarts, we should set BRD(I) as 25000000/(16*115200) = 13 but serial8250_do_set_divisor() will set BRD(I) as DIV_ROUND_CLOSEST(25*1000000, 16*115200)) = 14 Thanks
