From: David Gibson <david@gibson.dropbear.id.au>
To: Bin Meng <bmeng.cn@gmail.com>
Cc: "Bin Meng" <bin.meng@windriver.com>,
"Philippe Mathieu-Daudé" <f4bug@amsat.org>,
qemu-ppc@nongnu.org, "Greg Kurz" <groug@kaod.org>,
"qemu-devel@nongnu.org Developers" <qemu-devel@nongnu.org>
Subject: Re: [PATCH v2 2/2] hw/ppc: e500: Fill in correct <clock-frequency> for the serial nodes
Date: Fri, 5 Feb 2021 10:51:30 +1100 [thread overview]
Message-ID: <20210204235130.GF4729@yekko.fritz.box> (raw)
In-Reply-To: <CAEUhbmWVCur36ZS4QNjiDfYrotsH-8=-uDn=rpxOiwAnwSGf6Q@mail.gmail.com>
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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
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next prev parent reply other threads:[~2021-02-05 0:02 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-03 14:24 [PATCH v2 1/2] hw/ppc: e500: Use a macro for the platform clock frequency Bin Meng
2021-02-03 14:24 ` [PATCH v2 2/2] hw/ppc: e500: Fill in correct <clock-frequency> for the serial nodes Bin Meng
2021-02-04 2:59 ` David Gibson
2021-02-04 5:05 ` Bin Meng
2021-02-04 23:51 ` David Gibson [this message]
2021-02-04 2:59 ` [PATCH v2 1/2] hw/ppc: e500: Use a macro for the platform clock frequency David Gibson
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