linux-kernel - Re: [PATCH v3 1/2] dt-bindings: i2c: exynos5: add exynosautov9-hsi2c compatible

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Message-ID: <589dbb7f-4f7c-0ae0-e899-04107accf23c@canonical.com>
Date:   Fri, 19 Nov 2021 09:57:50 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
To:     Jaewon Kim <jaewon02.kim@...sung.com>,
        Wolfram Sang <wsa@...nel.org>, Rob Herring <robh+dt@...nel.org>
Cc:     linux-samsung-soc@...r.kernel.org, linux-i2c@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        chanho61.park@...sung.com, linux-arm-kernel@...ts.infradead.org,
        Sam Protsenko <semen.protsenko@...aro.org>
Subject: Re: [PATCH v3 1/2] dt-bindings: i2c: exynos5: add exynosautov9-hsi2c
 compatible

On 12/11/2021 02:01, Jaewon Kim wrote:
> This patch adds new "samsung,exynosautov9-hsi2c" compatible.
> It is for i2c compatible with HSI2C available on Exynos SoC with USI.
> 
> Signed-off-by: Jaewon Kim <jaewon02.kim@...sung.com>
> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>

Thanks Jaewon for your patch. After more discussions and remarks from
David, I think we should go with dedicated USI driver instead of using
sysreg/syscon in every I2C/UART/SPI.

Therefore I want to remove my reviewed-by and instead ask to work on
dedicated USI driver (option 1 from Chanho's email).

It's not that this solution is anything bad, just it won't be flexible
to support USIv1. It will also lead to duplicated - and possibly
conflicting - USI configuration in each of drivers (I2C/UART/SPI).

> ---
>  Documentation/devicetree/bindings/i2c/i2c-exynos5.txt | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/i2c/i2c-exynos5.txt b/Documentation/devicetree/bindings/i2c/i2c-exynos5.txt
> index 2dbc0b62daa6..39f4067d9d1f 100644
> --- a/Documentation/devicetree/bindings/i2c/i2c-exynos5.txt
> +++ b/Documentation/devicetree/bindings/i2c/i2c-exynos5.txt
> @@ -14,6 +14,8 @@ Required properties:
>  				on Exynos5260 SoCs.
>  	-> "samsung,exynos7-hsi2c", for i2c compatible with HSI2C available
>  				on Exynos7 SoCs.
> +	-> "samsung,exynosautov9-hsi2c", for i2c compatible with HSI2C available
> +				on ExynosAutov9 SoCs.
>  
>    - reg: physical base address of the controller and length of memory mapped
>      region.
> @@ -31,6 +33,11 @@ Optional properties:
>         at 100khz.
>      -> If specified, the bus operates in high-speed mode only if the
>         clock-frequency is >= 1Mhz.
> +  - samsung,sysreg : system registers controller phandle to control USI.
> +    -> If I2C integrated to USI(Universal Serial Interface), this property
> +       is required. When using Exynos USI block, it needs to select which type
> +       of Serial IPs(UART, SPI, I2C) to use with system register. So, it
> +       requires samsung,sysreg phandle and offset value of system register.
>  
>  Example:
>  
> 


Best regards,
Krzysztof