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Date: Fri, 6 Jul 2018 11:18:49 +1000
From: David Gibson <david@gibson.dropbear.id.au>
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Subject: Re: [Qemu-devel] [PATCH] sam460ex: Add comment explaining ignored
 errors from fdt operations
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Guenter Roeck <linux@roeck-us.net>, Alexander Graf <agraf@suse.de>, qemu-ppc@nongnu.org, qemu-devel@nongnu.org, BALATON Zoltan <balaton@eik.bme.hu>, Pilippe =?iso-8859-1?Q?Mathieu-Daud=E9?= <f4bug@amsat.org>


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On Thu, Jul 05, 2018 at 04:06:28PM +0200, Paolo Bonzini wrote:
> On 05/07/2018 15:51, Guenter Roeck wrote:
> > +        /* Failure to set serial port clocks is not fatal, so just ign=
ore
> > +         * errors when trying to do so.
> > +         */
> > +        (void)fdt_setprop_cell(fdt, offset, "clock-frequency", UART_FR=
EQ);
> >          offset =3D fdt_node_offset_by_compatible(fdt, offset, "ns16550=
");
>=20
> Ok, but why would it even fail?  Maybe it's not this case, but even if
> it's not fatal for the OS, generating different device trees silently
> seems like a recipe for Heisenbugs.

Yes, quite.  Especially since the most likely errors I can see here
would actually indicate something has already gone horribly wrong with
the device tree construction, so a missing clock-frequency is the
least of our troubles.

I think using _FDT() here would be a better approach.

--=20
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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