Date: Wed, 20 Apr 2016 12:31:22 +0100
From: Will Deacon <will.deacon@arm.com>
To: Tai Tri Nguyen <ttnguyen@apm.com>
Cc: Rob Herring <robh@kernel.org>, Mark Rutland <mark.rutland@arm.com>,
        catalin.marinas@arm.com, linux-kernel@vger.kernel.org,
        devicetree@vger.kernel.org,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        patches <patches@apm.com>
Subject: Re: [PATCH v2 2/4] Documentation: Add documentation for APM X-Gene
 SoC PMU DTS binding
Message-ID: <20160420113121.GE2514@arm.com>
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On Mon, Apr 18, 2016 at 01:04:53PM -0700, Tai Tri Nguyen wrote:
> >> +Required properties for MCB subnode:
> >> +- compatible         : Shall be "apm,xgene-pmu-mcb".
> >> +- reg                        : First resource shall be the MCB PMU resource.
> >> +- index                      : Instance number of the MCB PMU.
> >> +
> >> +Required properties for MC subnode:
> >> +- compatible         : Shall be "apm,xgene-pmu-mc".
> >> +- reg                        : First resource shall be the MC PMU resource.
> >> +- index                      : Instance number of the MC PMU.
> >
> > Don't use indexes. You probably need phandles to the nodes these are
> > related to.
> >
> > How many variations of child nodes do you expect to have? 2, 10, 50? You
> > might want to just collapse all this down to a single node and put this
> > information in the driver if it is fixed for each SoC and there's only a
> > handful.
> >
> 
> For each kind of PMU, for example memory controller PMU, I expect to
> have the number of instances up to 8.
> They are actually all independent PMU nodes and have their own CSR memory bases.
> The indexes are used for exposing the devices to perf user only. It
> doesn't have an impact on the programming model.
> Mark also had the same concern.

Regardless, I'll need an ack from Rob or Mark before I can merge this.

Will