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

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Message-ID: <821fd47f-6703-4f05-8fa5-3b1e04555af7@microchip.com>
Date:   Tue, 5 Jul 2022 19:31:55 +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>,
        <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 20:28, Conor.Dooley@...rochip.com wrote:
> 
> 
> 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.

s/firmware/bootloader

> 
>>
>> 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
>>>
>>>
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