RE: [PATCH v6 1/2] dt-bindings: i2c: aspeed: support for AST2600-i2cv2

Ryan Chen
2023-03-01T11:35:12Z

Hello Krzysztof,

> -----Original Message-----
> From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> Sent: Monday, February 27, 2023 4:25 PM
> To: Ryan Chen <ryan_chen@aspeedtech.com>; Andrew Jeffery
> <andrew@aj.id.au>; Brendan Higgins <brendan.higgins@linux.dev>; Benjamin
> Herrenschmidt <benh@kernel.crashing.org>; Joel Stanley <joel@jms.id.au>;
> Rob Herring <robh+dt@kernel.org>; Krzysztof Kozlowski
> <krzysztof.kozlowski+dt@linaro.org>; Philipp Zabel <p.zabel@pengutronix.de>;
> linux-i2c@vger.kernel.org; openbmc@lists.ozlabs.org;
> devicetree@vger.kernel.org; linux-arm-kernel@lists.infradead.org;
> linux-aspeed@lists.ozlabs.org; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH v6 1/2] dt-bindings: i2c: aspeed: support for AST2600-i2cv2
>
> On 26/02/2023 04:13, Ryan Chen wrote:
> > Add ast2600-i2cv2 compatible and aspeed,global-regs, aspeed,timeout
> > aspeed,xfer-mode description for ast2600-i2cv2.
> >
> > Signed-off-by: Ryan Chen <ryan_chen@aspeedtech.com>
> > ---
> > .../devicetree/bindings/i2c/aspeed,i2c.yaml | 44 +++++++++++++++++++
> > 1 file changed, 44 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/i2c/aspeed,i2c.yaml
> > b/Documentation/devicetree/bindings/i2c/aspeed,i2c.yaml
> > index f597f73ccd87..75de3ce41cf5 100644
> > --- a/Documentation/devicetree/bindings/i2c/aspeed,i2c.yaml
> > +++ b/Documentation/devicetree/bindings/i2c/aspeed,i2c.yaml
> > @@ -49,6 +49,25 @@ properties:
> > description:
> > states that there is another master active on this bus
> >
> > + aspeed,timeout:
> > + type: boolean
> > + description: I2C bus timeout enable for master/slave mode
>
> Nothing improved here in regards to my last comment.

Yes, as I know your require is about " DT binding to represent hardware setup"
So I add more description about aspeed,timeout as blow.

ASPEED SOC chip is server product, i2c bus may have fingerprint connect to another board. And also support hotplug.
The following is board-specific design example.
Board A Board B
------------------------- ------------------------
|i2c bus#1(master/slave) <===fingerprint ===> i2c bus#x (master/slave)|
|i2c bus#2(master)-> tmp i2c device | | |
|i2c bus#3(master)-> adc i2c device | | |
------------------------- ------------------------

aspeed,timout properites:
For example I2C controller as slave mode, and suddenly disconnected.
Slave state machine will keep waiting for master clock in for rx/tx transmit.
So it need timeout setting to enable timeout unlock controller state.
And in another side. In Master side also need avoid suddenly slave miss(un-plug), Master will timeout and release the SDA/SCL.

Do you mean add those description into ore aspeed,timout properites description?

>
> > +
> > + aspeed,xfer-mode:
> > + description: |
> > + I2C bus transfer mode selection.
> > + - "byte": I2C bus byte transfer mode.
> > + - "buffered": I2C bus buffer register transfer mode.
> > + - "dma": I2C bus dma transfer mode (default)
> > + items:
> > + enum: [byte, buffered, dma]
> > + maxItems: 1
>
> Drop, not an array.
>
> > + $ref: /schemas/types.yaml#/definitions/non-unique-string-array
>
> Wrong ref. This is not an array, but one string.

Sorry, I can't catch your "one string" point.
Could you point me what ref I can refer to?
That I can check into Linux example. Thanks a lot.
>
> > +
> > + aspeed,global-regs:
> > + $ref: /schemas/types.yaml#/definitions/phandle
> > + description: The phandle of i2c global register node.
> > +
> > required:
> > - reg
> > - compatible
> > @@ -57,6 +76,19 @@ required:
> >
> > unevaluatedProperties: false
> >
> > +if:
>
> This should be under allOf (in this location)
>
> > + properties:
> > + compatible:
> > + contains:
> > + const: aspeed,ast2600-i2cv2
> > +
> > +then:
> > + properties:
> > + reg:
> > + minItems: 2
> > + required:
> > + - aspeed,global-regs
>
> else:
> aspeed,global-regs: false
> and the same for other v2 properties
>

Does modify by following?

allOf:
-if:
properties:
compatible:
contains:
const: aspeed,ast2600-i2cv2

then:
properties:
reg:
minItems: 2
required:
- aspeed,global-regs
else:
- aspeed,global-regs: false
-aspeed,timeout: false
- aspeed,xfer-mode: false

> > +
> > examples:
> > - |
> > #include <dt-bindings/clock/aspeed-clock.h>
> > @@ -71,3 +103,15 @@ examples:
> > interrupts = <0>;
> > interrupt-parent = <&i2c_ic>;
> > };
> > + - |
> > + #include <dt-bindings/interrupt-controller/arm-gic.h>
> > + i2c1: i2c@80 {
> > + #address-cells = <1>;
> > + #size-cells = <0>;
> > + compatible = "aspeed,ast2600-i2cv2";
> > + reg = <0x80 0x80>, <0xc00 0x20>;
> > + interrupts = <GIC_SPI 110 IRQ_TYPE_LEVEL_HIGH>;
> > + aspeed,global-regs = <&i2c_global>;
> > + clocks = <&syscon ASPEED_CLK_APB>;
> > + resets = <&syscon ASPEED_RESET_I2C>;
> > + };
>
Best regards,
Ryan Chen.