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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Rob Herring <robh+dt@kernel.org>, Nicholas Piggin <npiggin@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
	Frank Rowand <frowand.list@gmail.com>
Subject: Re: [PATCH 2/3] of/fdt: introduce of_scan_flat_dt_subnodes and of_get_flat_dt_phandle
Date: Thu, 06 Apr 2017 06:58:01 +1000	[thread overview]
Message-ID: <1491425881.4166.90.camel@kernel.crashing.org> (raw)
In-Reply-To: <CAL_JsqLEvjb8S-+-JEa4ALHeCWHiR1A_4ur9kd3pBRJaFYWVKw@mail.gmail.com>

On Wed, 2017-04-05 at 10:58 -0500, Rob Herring wrote:
> Well, I'd like to avoid expanding usage of flat DT parsing in the
> kernel. But you could just put this function into arch/powerpc and I'd
> never see it, but I like that even less. Mainly, I just wanted to
> raise the point.
> 
> Your argument works until you need that setup in assembly code, then
> you are in the situation that you need to either handle the setup in
> bootloader/firmware or have an simple way to determine that condition.

The main issue is that changing that is a very very invasive change in
an extremely fragile and rather nasty area of code shared by 32 and 64-
bit for which we don't even have easy access to all the machines to
test with anymore :)

It's probably not impossible, but it would delay the new cpu feature
stuff that Nick is making by a lot, probably monthes, making it nearly
impossible to get back into distros etc... 

So while it might be something to consider, I would definitely keep
that as a separate unit of work to do later.

Cheers,
Ben.

  reply	other threads:[~2017-04-05 20:58 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-05 12:37 [PATCH 0/3] latest cpufeatures patch series Nicholas Piggin
2017-04-05 12:37 ` [PATCH 1/3] powerpc/64s: POWER9 no LPCR VRMASD bits Nicholas Piggin
2017-04-05 12:37 ` [PATCH 2/3] of/fdt: introduce of_scan_flat_dt_subnodes and of_get_flat_dt_phandle Nicholas Piggin
     [not found]   ` <CAL_JsqK4zbACwWVb-rsrvBb4hjBCexrqKRKrzSiZrZH5w=bKqQ@mail.gmail.com>
     [not found]     ` <20170406003251.533e2845@roar.ozlabs.ibm.com>
2017-04-05 15:58       ` Rob Herring
2017-04-05 20:58         ` Benjamin Herrenschmidt [this message]
2017-04-06  0:38           ` Nicholas Piggin
2017-04-06 14:09             ` Rob Herring
2017-04-10  5:43               ` Nicholas Piggin
2017-04-10 13:42                 ` Rob Herring
2017-04-07  6:40         ` Michael Ellerman
2017-04-05 12:37 ` [PATCH 3/3] powerpc/64s: cpufeatures: add initial implementation for cpufeatures Nicholas Piggin
2017-04-06  8:59   ` kbuild test robot
2017-04-10  7:21   ` Nicholas Piggin
  -- strict thread matches above, loose matches on Subject: below --
2017-04-12 17:48 [PATCH 0/3] cpufeatures merge candidate Nicholas Piggin
2017-04-12 17:48 ` [PATCH 2/3] of/fdt: introduce of_scan_flat_dt_subnodes and of_get_flat_dt_phandle Nicholas Piggin

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