Re: [RFC PATCH 04/11] i2c: dt-bindings: configuration settings

Krzysztof Kozlowski
2024-05-07T06:35:06Z

On 07/05/2024 00:51, Krishna Yarlagadda wrote:
> I2C interface timing registers are configured using config setting
> framework. Document available properties for Tegra I2C controllers.
>
> Signed-off-by: Krishna Yarlagadda <kyarlagadda@nvidia.com>
> ---
> .../bindings/i2c/nvidia,tegra20-i2c.yaml | 104 ++++++++++++++++++
> 1 file changed, 104 insertions(+)
>

You called it RFC, so not ready for review, thus just few remarks.

Please use subject prefixes matching the subsystem. You can get them for
example with `git log --oneline -- DIRECTORY_OR_FILE` on the directory
your patch is touching. For bindings, the preferred subjects are
explained here:
https://www.kernel.org/doc/html/latest/devicetree/bindings/submitting-patches.html#i-for-patch-submitters

> diff --git a/Documentation/devicetree/bindings/i2c/nvidia,tegra20-i2c.yaml b/Documentation/devicetree/bindings/i2c/nvidia,tegra20-i2c.yaml
> index 424a4fc218b6..3b22e75e5aa0 100644
> --- a/Documentation/devicetree/bindings/i2c/nvidia,tegra20-i2c.yaml
> +++ b/Documentation/devicetree/bindings/i2c/nvidia,tegra20-i2c.yaml
> @@ -119,6 +119,96 @@ properties:
> - const: rx
> - const: tx
>
> + config:
> + description: Config settings for I2C devices enlisted with I2C controller.
> + Config setting is the configuration based on chip/board/system
> + characterization on interface/controller settings. This is needed for
> + - making the controller internal configuration to better perform
> + - making the interface to work proper by setting drive strength, slew
> + rates etc
> + - making the low power leakage.
> + There are two types of recommended configuration settings
> + - Controller register specific for internal operation of controller.
> + - Pad control/Pinmux/pincontrol registers for interfacing.
> + These configurations can further be categorized as static and dynamic.
> + - Static config does not change until a controller is reset.
> + - Dynamic config changes based on mode or condition, controller is
> + operating in.
> + I2C has configuration based on clock speed and has below modes.
> + - common is set on all speeds and can be overridden by speed mode.
> + - high is set when clock mode is high speed.
> + - fastplus is set when clock mode is fast plus.
> + - fast is set when clock mode is fast mode.
> + - standard is set when clock mode is standard mode.
> + $ref: /schemas/misc/nvidia,tegra-config-settings.yaml
> + unevaluatedProperties: false
> + properties:
> + nvidia,i2c-clk-divisor-hs-mode:
> + description: I2C clock divisor for HS mode.

So you decided to implement clocks in DT? No.

> + $ref: /schemas/types.yaml#/definitions/uint32
> + minimum: 0
> + maximum: 0xffff

Anyway divisors, clock rates and everything is human-readable so in
decimal, not hex.

There are also several issues further, like using wrong units (time has
a unit), but since this is RFC, I will just NAK.

Best regards,
Krzysztof