Re: [PATCH v3 3/6] dt-bindings: devfreq: Add bindings for imx ddr controller

[Leonard Crestez <leonard.crestez@xxxxxxx>]

On 05.11.2019 00:21, Rob Herring wrote:
> On Thu, Oct 31, 2019 at 11:50:24PM +0200, Leonard Crestez wrote:
>> Add devicetree bindings for the i.MX DDR Controller on imx8m series
>> chips. It supports dynamic frequency switching between multiple data
>> rates and this is exposed to Linux via the devfreq subsystem.
>>
>> Signed-off-by: Leonard Crestez <leonard.crestez@xxxxxxx>
>> ---
>>   .../devicetree/bindings/devfreq/imx-ddrc.yaml | 60 +++++++++++++++++++
> 
> .../bindings/memory-controllers/

Okay, but I'm not sure about the rules here. Usually there is a 1:1 
mapping between subsystems and bindings directory but I guess devfreq is 
odd since it's not really a physical class of device.

I saw there is also a drivers/memory and there is already a 
devfreq-using driver in there (EXYNOS5422_DMC).

It's not clear if my driver fits in there; as far as I can see the only 
"core" functionality in drivers/memory is parsing DDR timings from DTS 
but for imx8m this is all controlled in firmware.

>>   1 file changed, 60 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/devfreq/imx-ddrc.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/devfreq/imx-ddrc.yaml b/Documentation/devicetree/bindings/devfreq/imx-ddrc.yaml
>> new file mode 100644
>> index 000000000000..31db204e6845
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/devfreq/imx-ddrc.yaml
>> @@ -0,0 +1,60 @@
>> +# SPDX-License-Identifier: GPL-2.0
> 
> For new bindings:
> 
> # SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> 
>> +%YAML 1.2
>> +---
>> +$id: https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fdevicetree.org%2Fschemas%2Fdevfreq%2Fimx-devfreq.yaml%23&amp;data=02%7C01%7Cleonard.crestez%40nxp.com%7Cba47e72161764d5a969a08d761755736%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C1%7C637085028918247356&amp;sdata=2DjKgyATOPu7qhzpOCfRrmUM0%2FSAQrV9R7AxZxib8gk%3D&amp;reserved=0
> 
> Run 'make dt_binding_check'. This will fail as the filename doesn't
> match.
> 
>> +$schema: https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fdevicetree.org%2Fmeta-schemas%2Fcore.yaml%23&amp;data=02%7C01%7Cleonard.crestez%40nxp.com%7Cba47e72161764d5a969a08d761755736%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C1%7C637085028918247356&amp;sdata=EbyVK2ZF6Z22vE%2F4LfIVv0S1LoMe7%2BxhM43H1i8nxtE%3D&amp;reserved=0
>> +
>> +title: i.MX DDR Controller
> 
> Perhaps i.MX8x as it's not all i.MX chips. And the filename too?

Ok, will rename to imx8m-ddrc since it's not even for all imx8.

>> +
>> +maintainers:
>> +  - Leonard Crestez <leonard.crestez@xxxxxxx>
>> +
>> +properties:
>> +  compatible:
>> +    items:
>> +      - enum:
>> +        - fsl,imx8mn-ddrc
>> +        - fsl,imx8mm-ddrc
>> +        - fsl,imx8mq-ddrc
>> +      - const: fsl,imx8m-ddrc
>> +
>> +  reg:
>> +    maxItems: 1
>> +
>> +  clocks:
>> +    maxItems: 4
>> +
>> +  clock-names:
>> +    items:
>> +      - const: dram_core
>> +      - const: dram_pll
>> +      - const: dram_alt
>> +      - const: dram_apb
> 
> Drop 'dram_'

OK

>> +
>> +  operating-points-v2: true
>> +
>> +  devfreq-events:
>> +    description: Phandle of PMU node
>> +    $ref: "/schemas/types.yaml#/definitions/phandle"
>> +
>> +required:
>> +  - reg
>> +  - compatible
>> +  - clocks
>> +  - clock-names
>> +
>> +additionalProperties: false
>> +
>> +examples:
>> +  - |
>> +    #include <dt-bindings/clock/imx8mm-clock.h>
>> +    ddrc: dram-controller@3d400000 {
>> +        compatible = "fsl,imx8mm-ddrc", "fsl,imx8m-ddrc";
>> +        reg = <0x3d400000 0x400000>;
>> +        clock-names = "dram_core", "dram_pll", "dram_alt", "dram_apb";
>> +        clocks = <&clk IMX8MM_CLK_DRAM_CORE>,
>> +                 <&clk IMX8MM_DRAM_PLL>,
>> +                 <&clk IMX8MM_CLK_DRAM_ALT>,
>> +                 <&clk IMX8MM_CLK_DRAM_APB>;
>> +        operating-points-v2 = <&ddrc_opp_table>;
>> +    };