Re: [PATCH v2 2/2] hw/ppc: e500: Fill in correct <clock-frequency> for the serial nodes

[David Gibson]

On Thu, Feb 04, 2021 at 01:05:19PM +0800, Bin Meng wrote:
> On Thu, Feb 4, 2021 at 12:58 PM David Gibson
> <david@gibson.dropbear.id.au> wrote:
> >
> > On Wed, Feb 03, 2021 at 10:24:48PM +0800, Bin Meng wrote:
> > > From: Bin Meng <bin.meng@windriver.com>
> > >
> > > At present the <clock-frequency> property of the serial node is
> > > populated with value zero. U-Boot's ns16550 driver is not happy
> > > about this, so let's fill in a meaningful value.
> >
> > Are you sure this is correct - that is that the serial clock is really
> > the same as the overall system clock?  Quite often there's some kind
> > of divider in between.
> >
> 
> Yes, see the U-Boot codes include/configs/qemu-ppce500.h
> 
> #define CONFIG_SYS_NS16550_CLK          (get_bus_freq(0))
> 
> get_bus_freq(0) eventually returns the platform clock frequency which is 
> 400MHz.
> 
> But the value doesn't matter anyway for QEMU. We don't emulate any
> baud rate specific thing for a serial port. We only need a sane value
> that is non-zero.

Understood.  Applied to ppc-for-6.0.

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

signature.asc
Description: PGP signature