Re: [PATCH v4 3/3] serial: 8250_dw: add fractional divisor support

2018-07-11 Thread Andy Shevchenko
On Wed, 2018-07-11 at 14:41 +0800, Jisheng Zhang wrote: > On Tue, 10 Jul 2018 19:19:21 +0300 Andy Shevchenko wrote: > > > +/* > > > + * divisor = div(I) + div(F) > > > + * "I" means integer, "F" means fractional > > > + * quot = div(I) = clk / (16 * baud) > > > + * frac = div(F) * 2^dlf_size > > >

Re: [PATCH v4 3/3] serial: 8250_dw: add fractional divisor support

2018-07-10 Thread Jisheng Zhang
Hi Andy, On Tue, 10 Jul 2018 19:19:21 +0300 Andy Shevchenko wrote: > On Tue, 2018-07-10 at 11:15 +0800, Jisheng Zhang wrote: > > For Synopsys DesignWare 8250 uart which version >= 4.00a, there's a > > valid divisor latch fraction register. The fractional divisor width is > > 4bits ~ 6bits. > > >

Re: [PATCH v4 3/3] serial: 8250_dw: add fractional divisor support

2018-07-10 Thread Andy Shevchenko
On Tue, 2018-07-10 at 11:15 +0800, Jisheng Zhang wrote: > For Synopsys DesignWare 8250 uart which version >= 4.00a, there's a > valid divisor latch fraction register. The fractional divisor width is > 4bits ~ 6bits. > > Now the preparation is done, it's easy to add the feature support. > This patc