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Date:   Wed, 30 Sep 2020 18:03:55 +0200
From:   Thierry Reding <thierry.reding@gmail.com>
To:     Dmitry Osipenko <digetx@gmail.com>
Cc:     Nicolin Chen <nicoleotsuka@gmail.com>, joro@8bytes.org,
        krzk@kernel.org, vdumpa@nvidia.com, jonathanh@nvidia.com,
        linux-tegra@vger.kernel.org, iommu@lists.linux-foundation.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 1/3] memory: tegra: Add
 devm_tegra_get_memory_controller()
Message-ID: <20200930160355.GC3833404@ulmo>
References: <20200930084258.25493-1-nicoleotsuka@gmail.com>
 <20200930084258.25493-2-nicoleotsuka@gmail.com>
 <20200930152320.GA3833404@ulmo>
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On Wed, Sep 30, 2020 at 06:53:06PM +0300, Dmitry Osipenko wrote:
> 30.09.2020 18:23, Thierry Reding =D0=BF=D0=B8=D1=88=D0=B5=D1=82:
> > On Wed, Sep 30, 2020 at 01:42:56AM -0700, Nicolin Chen wrote:
> >> From: Dmitry Osipenko <digetx@gmail.com>
> >>
> >> Multiple Tegra drivers need to retrieve Memory Controller and hence th=
ere
> >> is quite some duplication of the retrieval code among the drivers. Let=
's
> >> add a new common helper for the retrieval of the MC.
> >>
> >> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> >> Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
> >> ---
> >>
> >> Changelog
> >> v2->v3:
> >>  * Replaced with Dimtry's devm_tegra_get_memory_controller()
> >> v1->v2:
> >>  * N/A
> >>
> >>  drivers/memory/tegra/mc.c | 39 +++++++++++++++++++++++++++++++++++++++
> >>  include/soc/tegra/mc.h    | 17 +++++++++++++++++
> >>  2 files changed, 56 insertions(+)
> >=20
> > Let's not add this helper, please. If a device needs a reference to the
> > memory controller, it should have a phandle to the memory controller in
> > device tree so that it can be looked up explicitly.
> >=20
> > Adding this helper is officially sanctioning that it's okay not to have
> > that reference and that's a bad idea.
>=20
> And please explain why it's a bad idea, I don't see anything bad here at
> all.

Well, you said yourself in a recent comment that we should avoid global
variables. devm_tegra_get_memory_controller() is nothing but a glorified
global variable.

Thierry

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