linux-kernel - Re: [PATCH v2 2/4] dt-bindings: Add TI SCI PM Domains

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Message-ID: <58120A04.2050501@ti.com>
Date:   Thu, 27 Oct 2016 09:07:00 -0500
From:   Dave Gerlach <d-gerlach@...com>
To:     Tero Kristo <t-kristo@...com>, Rob Herring <robh@...nel.org>
CC:     Ulf Hansson <ulf.hansson@...aro.org>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Kevin Hilman <khilman@...nel.org>, Nishanth Menon <nm@...com>,
        <devicetree@...r.kernel.org>,
        Santosh Shilimkar <ssantosh@...nel.org>,
        Keerthy <j-keerthy@...com>, <linux-pm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        Russell King <rmk+kernel@...linux.org.uk>,
        Sudeep Holla <sudeep.holla@....com>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2 2/4] dt-bindings: Add TI SCI PM Domains

On 10/27/2016 04:02 AM, Tero Kristo wrote:
> On 27/10/16 01:04, Rob Herring wrote:
>> On Wed, Oct 19, 2016 at 03:33:45PM -0500, Dave Gerlach wrote:
>>> Add a generic power domain implementation, TI SCI PM Domains, that
>>> will hook into the genpd framework and allow the TI SCI protocol to
>>> control device power states.
>>>
>>> Also, provide macros representing each device index as understood
>>> by TI SCI to be used in the device node power-domain references.
>>> These are identifiers for the K2G devices managed by the PMMC.
>>>
>>> Signed-off-by: Nishanth Menon <nm@...com>
>>> Signed-off-by: Dave Gerlach <d-gerlach@...com>
>>> ---
>>>  .../devicetree/bindings/soc/ti/sci-pm-domain.txt   | 54 +++++++++++++
>>>  MAINTAINERS                                        |  2 +
>>>  include/dt-bindings/genpd/k2g.h                    | 90 ++++++++++++++++++++++
>>>  3 files changed, 146 insertions(+)
>>>  create mode 100644 Documentation/devicetree/bindings/soc/ti/sci-pm-domain.txt
>>>  create mode 100644 include/dt-bindings/genpd/k2g.h
>>>
>>> diff --git a/Documentation/devicetree/bindings/soc/ti/sci-pm-domain.txt
>>> b/Documentation/devicetree/bindings/soc/ti/sci-pm-domain.txt
>>> new file mode 100644
>>> index 000000000000..32f38a349656
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/soc/ti/sci-pm-domain.txt
>>> @@ -0,0 +1,54 @@
>>> +Texas Instruments TI-SCI Generic Power Domain
>>> +---------------------------------------------
>>> +
>>> +Some TI SoCs contain a system controller (like the PMMC, etc...) that is
>>> +responsible for controlling the state of the IPs that are present.
>>> +Communication between the host processor running an OS and the system
>>> +controller happens through a protocol known as TI-SCI [1]. This pm domain
>>> +implementation plugs into the generic pm domain framework and makes use of
>>> +the TI SCI protocol power on and off each device when needed.
>>> +
>>> +[1] Documentation/devicetree/bindings/arm/keystone/ti,sci.txt
>>> +
>>> +PM Domain Node
>>> +==============
>>> +The PM domain node represents the global PM domain managed by the PMMC,
>>> +which in this case is the single implementation as documented by the generic
>>> +PM domain bindings in Documentation/devicetree/bindings/power/power_domain.txt.
>>> +
>>> +Required Properties:
>>> +--------------------
>>> +- compatible: should be "ti,sci-pm-domain"
>>> +- #power-domain-cells: Must be 0.
>>> +- ti,sci: Phandle to the TI SCI device to use for managing the devices.
>>> +
>>> +Example:
>>> +--------------------
>>> +k2g_pds: k2g_pds {
>>> +        compatible = "ti,sci-pm-domain";
>>> +        #power-domain-cells = <0>;
>>> +        ti,sci = <&pmmc>;
>>> +};
>>
>> Why not just make the PMMC node be the power-domain provider itself? If
>> not that, then make this a child node of it. The same comment applies to
>> all the SCI functions, but I guess I've already acked some of them.
> 
> This seems to be a bug in this documentation actually. ti,sci handle is no
> longer supported, and all the sci stuff must be under the parent sci node.
> 
>>
>> I really don't like reviewing all these TI SCI bindings one by one. Each
>> one on its own seems fine, but I don't see the full picture.
> 
> The full picture is represented under the documentation for the main protocol
> support itself. See this patch:
> 
> https://patchwork.kernel.org/patch/9383281/
> 
> Copy pasted here as ref:
> 
> Example (K2G):
> -------------
>         pmmc: pmmc {
>                 compatible = "ti,k2g-sci";
>                 ...
> 
>                 my_clk_node: clk_node {
>                         ...
>                         ...
>                 };
> 
>                 my_pd_node: pd_node {
>                         ...
>                         ...
>                 };
>         };
> 
> 

Yes my bad I will fix this in V3 once we straighten out the ID portion of the
binding.

Regards,
Dave