Re: [PATCH 1/4] net: dsa: Change DT bindings for Vitesse VSC73xx switches

[Andrew Lunn]

On Mon, Jul 01, 2019 at 05:27:20PM +0200, Pawel Dembicki wrote:
> This commit document changes after split vsc73xx driver into core and
> spi part. The change of DT bindings is required for support the same
> vsc73xx chip, which need PI bus to communicate with CPU. It also

SPI

> introduce how to use vsc73xx platform driver.
> 
> Signed-off-by: Pawel Dembicki <paweldembicki@xxxxxxxxx>
> ---
>  .../bindings/net/dsa/vitesse,vsc73xx.txt      | 74 ++++++++++++++++---
>  1 file changed, 64 insertions(+), 10 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/net/dsa/vitesse,vsc73xx.txt b/Documentation/devicetree/bindings/net/dsa/vitesse,vsc73xx.txt
> index ed4710c40641..c6a4cd85891c 100644
> --- a/Documentation/devicetree/bindings/net/dsa/vitesse,vsc73xx.txt
> +++ b/Documentation/devicetree/bindings/net/dsa/vitesse,vsc73xx.txt
> @@ -2,8 +2,8 @@ Vitesse VSC73xx Switches
>  ========================
>  
>  This defines device tree bindings for the Vitesse VSC73xx switch chips.
> -The Vitesse company has been acquired by Microsemi and Microsemi in turn
> -acquired by Microchip but retains this vendor branding.
> +The Vitesse company has been acquired by Microsemi and Microsemi has
> +been acquired Microchip but retains this vendor branding.
>  
>  The currently supported switch chips are:
>  Vitesse VSC7385 SparX-G5 5+1-port Integrated Gigabit Ethernet Switch
> @@ -11,16 +11,26 @@ Vitesse VSC7388 SparX-G8 8-port Integrated Gigabit Ethernet Switch
>  Vitesse VSC7395 SparX-G5e 5+1-port Integrated Gigabit Ethernet Switch
>  Vitesse VSC7398 SparX-G8e 8-port Integrated Gigabit Ethernet Switch
>  
> -The device tree node is an SPI device so it must reside inside a SPI bus
> -device tree node, see spi/spi-bus.txt
> +This switch could have two different management interface.
> +
> +If SPI interface is used, the device tree node is an SPI device so it must
> +reside inside a SPI bus device tree node, see spi/spi-bus.txt
> +
> +If Platform driver is used, the device tree node is an platform device so it
> +must reside inside a platform bus device tree node.
>  
>  Required properties:
>  
> -- compatible: must be exactly one of:
> -	"vitesse,vsc7385"
> -	"vitesse,vsc7388"
> -	"vitesse,vsc7395"
> -	"vitesse,vsc7398"

You cannot remove these. It will break backwards compatibility.
Adding new compatible strings is fine, but you cannot remove existing
ones.

	Andrew