From: Arnd Bergmann <arnd@arndb•de>
To: linuxppc-dev@ozlabs•org
Cc: Timur Tabi <timur@freescale•com>
Subject: Re: [PATCH v2] qe: add ability to upload QE firmware
Date: Thu, 6 Dec 2007 01:17:14 +0100 [thread overview]
Message-ID: <200712060117.14768.arnd@arndb.de> (raw)
In-Reply-To: <47573CCE.4000606@freescale.com>
On Thursday 06 December 2007, Timur Tabi wrote:
> > In that case, I think it
> > would really be better to just put the blob into the tree and only
> > have the fw loading code in the kernel instead of duplicating it in the=
boot
> > loader.
>=20
> That would require the firmware to present in RAM for all time, since the=
device=20
> tree cannot be unloaded.
Yes, that's a backdraw of my approach, but in the case of spidernet, it was=
only
an insignificant amount of RAM. Don't know what sizes of RAM and QE firmware
to expect typically on the machines you care about.
> Besides, you might need to have the firmware loaded in =20
> U-Boot anyway. =A0If your console is connected to the QE, then you'll nee=
d the=20
> UART firmware loaded before you can see anything. =A0That's why U-Boot ne=
eds its=20
> own version.
Right, so you can't really get around having it in some boot loaders at lea=
st.
IIRC you said that the firmware is only needed for serial output on some ch=
ips
but not on others. What about the case where you don't need it for serial b=
ut
still want to provide it by the firmware, and perhaps use something other t=
han
U-boot? Is that relevant?
I'm not trying to convince you of this if it's completely pointless for
all your systems, just want to make sure you're aware of this option,
because spending a few extra code lines on it now may save you some trouble
if you need this later.
> > Regarding the question whether the firmware should be a device node or
> > a property of another node, I'd prefer a simple property, because the
> > firmware itself is not really a device you can access, but I don't care
> > much about that.
>=20
> Technically, the firmware could be considered a device on the QE, because=
it's=20
> loaded into I-RAM and it can significantly alter the behavior of the devi=
ce.=20
Well, it doesn't have any of the standard properties like registers or inte=
rrupts
though.
> Having it its own node also lets me compartmentalize it. =A0If I want to =
expand=20
> the node and add more properties, it's cleaner.
Yes, that makes a lot of sense.
Arnd <><
next prev parent reply other threads:[~2007-12-06 0:17 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-12-05 22:41 [PATCH v2] qe: add ability to upload QE firmware Timur Tabi
2007-12-05 23:31 ` Arnd Bergmann
2007-12-05 23:37 ` Timur Tabi
2007-12-05 23:56 ` Arnd Bergmann
2007-12-06 0:05 ` Timur Tabi
2007-12-06 0:17 ` Arnd Bergmann [this message]
2007-12-06 15:03 ` Timur Tabi
2007-12-06 15:31 ` Arnd Bergmann
2007-12-06 15:46 ` Timur Tabi
2007-12-06 15:58 ` Arnd Bergmann
2007-12-06 15:59 ` Timur Tabi
2007-12-06 16:02 ` Kumar Gala
2007-12-06 16:12 ` Timur Tabi
2007-12-06 17:25 ` Timur Tabi
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