[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [PATCH v2 2/2] hw/ppc: e500: Fill in correct <clock-frequency> for t
From: |
Bin Meng |
Subject: |
Re: [PATCH v2 2/2] hw/ppc: e500: Fill in correct <clock-frequency> for the serial nodes |
Date: |
Thu, 4 Feb 2021 13:05:19 +0800 |
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.
Regards,
Bin