linux-kernel - Re: [PATCH 5/6] gpio: mvebu: Add support for the Armada 7K/8K SoCs

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Date:   Fri, 19 May 2017 17:27:36 +0100
From:   Russell King - ARM Linux <linux@...linux.org.uk>
To:     Gregory CLEMENT <gregory.clement@...e-electrons.com>
Cc:     Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
        Alexandre Courbot <gnurou@...il.com>,
        Jason Cooper <jason@...edaemon.net>,
        Andrew Lunn <andrew@...n.ch>,
        Linus Walleij <linus.walleij@...aro.org>,
        Omri Itach <omrii@...vell.com>, linux-kernel@...r.kernel.org,
        Nadav Haklai <nadavh@...vell.com>, linux-gpio@...r.kernel.org,
        devicetree@...r.kernel.org, Rob Herring <robh+dt@...nel.org>,
        Neta Zur Hershkovits <neta@...vell.com>,
        Kostya Porotchkin <kostap@...vell.com>,
        Shadi Ammouri <shadi@...vell.com>,
        Marcin Wojtas <mw@...ihalf.com>,
        linux-arm-kernel@...ts.infradead.org,
        Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
Subject: Re: [PATCH 5/6] gpio: mvebu: Add support for the Armada 7K/8K SoCs

On Fri, May 19, 2017 at 05:24:10PM +0100, Russell King - ARM Linux wrote:
> On Fri, May 19, 2017 at 06:09:24PM +0200, Gregory CLEMENT wrote:
> > The Armada 7K and 8K SoCs use the same gpio controller as most of the
> > other mvebu SoCs. However, the main difference is that the GPIO
> > controller is part of a bigger system controller, and a syscon is used to
> > control the overall system controller. Therefore, the driver needs to be
> > adjusted to retrieve the regmap of the syscon to access registers, and
> > account for the fact that registers are located at a certain offset
> > within the regmap.
> > 
> > This commit add the support of the syscon and introduce a new variant for
> > this case.
> 
> Do you really need all this complexity of merging what seems to be two
> GPIO devices into one for DT purposes?  The device itself appears to be
> two instances of the orion-gpio controller, one at 0x100 into the
> system controller and a second one at 0x140.
> 
> If you instantiate two orion-gpio controllers, then you don't need to
> add the "mvchip->offset" stuff.
> 
> I'd also say that it was the more correct approach, rather than adding
> more complexity to GPIO drivers to support whatever incarnation comes
> next.

Hmm, in fact, mvebu->offset always appears to be zero in this driver,
so I think the changes that add this member are entirely rendundant to
the function of this patch.

-- 
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