linux-kernel - Re: [PATCH v3 2/4] dt-bindings: Add TI SCI PM Domains

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Date:   Thu, 26 Jan 2017 10:00:32 -0600
From:   Rob Herring <robh@...nel.org>
To:     Dave Gerlach <d-gerlach@...com>
Cc:     Ulf Hansson <ulf.hansson@...aro.org>,
        Kevin Hilman <khilman@...libre.com>,
        Tero Kristo <t-kristo@...com>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Nishanth Menon <nm@...com>, Keerthy <j-keerthy@...com>,
        Russell King <rmk+kernel@...linux.org.uk>,
        Sudeep Holla <sudeep.holla@....com>,
        Santosh Shilimkar <ssantosh@...nel.org>,
        Lokesh Vutla <lokeshvutla@...com>
Subject: Re: [PATCH v3 2/4] dt-bindings: Add TI SCI PM Domains

On Thu, Jan 26, 2017 at 9:09 AM, Dave Gerlach <d-gerlach@...com> wrote:
> On 01/25/2017 04:32 PM, Rob Herring wrote:
>>
>> On Wed, Jan 25, 2017 at 10:59 AM, Dave Gerlach <d-gerlach@...com> wrote:

[...]

>>> because genpd_xlate_simple only checks that the phandle is zero so that
>>> it
>>> can fail if it is not, but there's no functional reason it needs to do
>>> this.
>>> The genpd framework works as it did before no matter what the cells are
>>> set
>>> to if using of_genpd_add_provider_simple. Then in the attach_dev callback
>>> inside the ti_sci_pm_domains driver instead of doing
>>>
>>>         ret = of_property_read_u32(np, "ti,sci-id", &idx);
>>>
>>> to read the ti,sc-id for a device into idx we can now do:
>>>
>>>        ret = of_parse_phandle_with_args(np, "power-domains",
>>>                                    "#power-domain-cells", 0, &pd_args);
>>>        idx = pd_args.args[0];
>>>
>>> or even simpler from within our driver
>>>
>>>         ret = of_property_read_u32_index(np, "power-domains", 1, &idx);
>>
>>
>> This you should not be doing. The client driver shouldn't care how
>> many cells or what their values are.
>
>
> Client drivers in other places use xlate functions, like in the
> drivers/reset framework, to interpret the cells. Is doing it this way really
> that different?

Oh, I was thinking the client driver, not the power domain controller
driver. NM.

Rob