linux-kernel - Re: [PATCH v2 3/6] dt/bindings: Add bindings for Tegra GMI controller

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Message-ID: <fca81faa-f7de-08df-00dd-dcc36d94aaf2@nvidia.com>
Date:   Fri, 30 Sep 2016 09:02:00 +0100
From:   Jon Hunter <jonathanh@...dia.com>
To:     Mirza Krak <mirza.krak@...il.com>, Rob Herring <robh@...nel.org>
CC:     Stephen Warren <swarren@...dotorg.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Alexandre Courbot <gnurou@...il.com>, <linux@...linux.org.uk>,
        <pdeschrijver@...dia.com>, Prashant Gaikwad <pgaikwad@...dia.com>,
        Michael Turquette <mturquette@...libre.com>,
        <sboyd@...eaurora.org>, <mark.rutland@....com>,
        <devicetree@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <linux-clk@...r.kernel.org>
Subject: Re: [PATCH v2 3/6] dt/bindings: Add bindings for Tegra GMI controller

Rob,

On 19/09/16 08:21, Mirza Krak wrote:
> 2016-09-06 12:32 GMT+02:00 Jon Hunter <jonathanh@...dia.com>:
>>
>> On 31/08/16 12:22, Mirza Krak wrote:
>>> 2016-08-30 19:06 GMT+02:00 Rob Herring <robh@...nel.org>:
>>
>> ...
>>
>>>>>                  nvidia,snor-cs = <4>;
>>>>
>>>> NAK, no custom CS properties.
>>
>> Ok, so ...
>>
>>> gmi@...90000 {
>>>         compatible = "nvidia,tegra20-gmi";
>>>         reg = <0x70009000 0x1000>;
>>>         #address-cells = <2>;
>>>         #size-cells = <1>;
>>>         clocks = <&tegra_car TEGRA20_CLK_NOR>;
>>>         clock-names = "gmi";
>>>         resets = <&tegra_car 42>;
>>>         reset-names = "gmi";
>>>         ranges = <4 0 0xd0000000 0xfffffff>;
>>>
>>>         status = "okay";
>>>
>>>         bus@4,0 {
>>>                 compatible = "simple-bus";
>>>                 #address-cells = <1>;
>>>                 #size-cells = <1>;
>>>                 ranges = <0 4 0 0x40000>;
>>>
>>>                 nvidia,snor-mux-mode;
>>>                 nvidia,snor-adv-inv;
>>>
>>>                 can@0 {
>>>                         reg = <0 0x100>;
>>>                         ...
>>>                 };
>>>
>>>                 can@...00 {
>>>                         reg = <0x40000 0x100>;
>>>                         ...
>>>                 };
>>>         };
>>> };
>>>
>>> Have I understood you correct?
>>>
>>> Also wanted to verify the example case where you only have on device
>>> connected to one CS#, from what I see in other implementations it
>>> seems OK to put the CS# in the reg property in that case. Is this
>>> correct?
>>>
>>> Example with one SJA1000 CAN controller connected to the GMI bus
>>> on CS4:
>>>
>>> gmi@...90000 {
>>>         compatible = "nvidia,tegra20-gmi";
>>>         reg = <0x70009000 0x1000>;
>>>         #address-cells = <2>;
>>>         #size-cells = <1>;
>>>         clocks = <&tegra_car TEGRA20_CLK_NOR>;
>>>         clock-names = "gmi";
>>>         resets = <&tegra_car 42>;
>>>         reset-names = "gmi";
>>>         ranges = <4 0 0xd0000000 0xfffffff>;
>>>
>>>         status = "okay";
>>>
>>>         can@4,0 {
>>>                 reg = <4 0 0x100>;
>>>                 nvidia,snor-mux-mode;
>>>                 nvidia,snor-adv-inv;
>>>                 ...
>>>         };
>>> };
>>>
>>> Jon, to be able to handle both cases in the driver we would first
>>> attempt to decode the CS# from the ranges property, and fallback to
>>> reg property if no ranges are defined. Does that sound reasonable?
>>
>> Given the above examples that may be supported, is there a
>> better/simpler way to extract the CS# than what Mirza is proposing? For
>> example, from the node-name unit-address?
>>
> 
> Hi.
> 
> I have been on vacation and now I am back and wanted to finalize these
> patch series.
> 
> So pinging this thread to see I we can agree on a solution.
> 
> Rob any comments to my proposal and Jon`s comment?

Can you comment on the above?

Cheers
Jon

-- 
nvpublic