linux-kernel - Re: [PATCH v4 05/14] dt-bindings: memory-controllers: add canaan k210 sram controller

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Date:   Tue, 5 Jul 2022 19:28:05 +0000
From:   <Conor.Dooley@...rochip.com>
To:     <robh@...nel.org>
CC:     <airlied@...ux.ie>, <daniel@...ll.ch>,
        <krzysztof.kozlowski+dt@...aro.org>, <thierry.reding@...il.com>,
        <sam@...nborg.org>, <Eugeniy.Paltsev@...opsys.com>,
        <vkoul@...nel.org>, <lgirdwood@...il.com>, <broonie@...nel.org>,
        <fancer.lancer@...il.com>, <daniel.lezcano@...aro.org>,
        <palmer@...belt.com>, <palmer@...osinc.com>,
        <paul.walmsley@...ive.com>, <aou@...s.berkeley.edu>,
        <Conor.Dooley@...rochip.com>, <masahiroy@...nel.org>,
        <damien.lemoal@...nsource.wdc.com>, <geert@...ux-m68k.org>,
        <niklas.cassel@....com>, <dillon.minfei@...il.com>,
        <joabreu@...opsys.com>, <dri-devel@...ts.freedesktop.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <dmaengine@...r.kernel.org>, <alsa-devel@...a-project.org>,
        <linux-riscv@...ts.infradead.org>
Subject: Re: [PATCH v4 05/14] dt-bindings: memory-controllers: add canaan k210
 sram controller



On 05/07/2022 20:23, Rob Herring wrote:
> On Fri, Jul 01, 2022 at 08:22:51PM +0100, Conor Dooley wrote:
>> From: Conor Dooley <conor.dooley@...rochip.com>
>>
>> The k210 U-Boot port has been using the clocks defined in the
>> devicetree to bring up the board's SRAM, but this violates the
>> dt-schema. As such, move the clocks to a dedicated node with
>> the same compatible string & document it.
>>
>> Signed-off-by: Conor Dooley <conor.dooley@...rochip.com>
>> ---
>>  .../memory-controllers/canaan,k210-sram.yaml  | 52 +++++++++++++++++++
>>  1 file changed, 52 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/memory-controllers/canaan,k210-sram.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/memory-controllers/canaan,k210-sram.yaml b/Documentation/devicetree/bindings/memory-controllers/canaan,k210-sram.yaml
>> new file mode 100644
>> index 000000000000..82be32757713
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/memory-controllers/canaan,k210-sram.yaml
>> @@ -0,0 +1,52 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/memory-controllers/canaan,k210-sram.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Canaan K210 SRAM memory controller
>> +
>> +description: |
> 
> Don't need '|'.
> 
>> +  The Canaan K210 SRAM memory controller is initialised and programmed by
>> +  firmware, but an OS might want to read its registers for error reporting
>> +  purposes and to learn about the DRAM topology.
> 
> How the OS going to do that? You don't have any way defined to access 
> the registers.

Eugh, copy paste. I'll rephrase in the respin. It should be "initialised by
firmware." There are no registers, only clocks.

> 
> Also, where is the SRAM address itself defined?

The actual sram is in the memory node.

> 
>> +
>> +maintainers:
>> +  - Conor Dooley <conor@...nel.org>
>> +
>> +properties:
>> +  compatible:
>> +    enum:
>> +      - canaan,k210-sram
>> +
>> +  clocks:
>> +    minItems: 1
>> +    items:
>> +      - description: sram0 clock
>> +      - description: sram1 clock
>> +      - description: aisram clock
>> +
>> +  clock-names:
>> +    minItems: 1
>> +    items:
>> +      - const: sram0
>> +      - const: sram1
>> +      - const: aisram
>> +
>> +required:
>> +  - compatible
>> +  - clocks
>> +  - clock-names
>> +
>> +additionalProperties: false
>> +
>> +examples:
>> +  - |
>> +    #include <dt-bindings/clock/k210-clk.h>
>> +    memory-controller {
>> +        compatible = "canaan,k210-sram";
>> +        clocks = <&sysclk K210_CLK_SRAM0>,
>> +                 <&sysclk K210_CLK_SRAM1>,
>> +                 <&sysclk K210_CLK_AI>;
>> +        clock-names = "sram0", "sram1", "aisram";
>> +    };
>> -- 
>> 2.37.0
>>
>>