Re: [PATCH 05/12] arm64: dts: Add I2C nodes for Hi3660

[Jarkko Nikula]

On 05/24/2017 05:34 AM, zhangfei wrote:
> Rob suggest add something like "hisilicon,hi3660-dw-i2c" as well.
> "The problem is dw-i2c does not give any clue as to what the
> configuration or version of the IP is.
> Is that fully discoverable with version/capability registers? If not
> then you need a specific compatible.
> Generally when we have not required them, it ends up being a problem
> later on."
Some features are discoverable from DW_IC_COMP_PARAM_1, 
DW_IC_COMP_VERSION and DW_IC_COMP_TYPE registers. Although my 
specification does not document what's inside of DW_IC_COMP_VERSION and 
DW_IC_COMP_TYPE but code is using them.

> While Documentation/devicetree/bindings/i2c/i2c-designware.txt
> compatible : should be "snps,designware-i2c"
>
> Besides, on Hikey960,
> [    3.822353] dw_readl(dev, DW_IC_COMP_VERSION)=0x3132302a
> [    3.827763] dw_readl(dev, DW_IC_COMP_TYPE)=0x44570140
> Are these two registers enough to distinguish version etc?
I've seen DW_IC_COMP_VERSION being 0x3131352a or 0x3132312a in our 
platforms. DW_IC_COMP_TYPE has the same value what you are seeing.

--
Jarkko