[PATCH] net: ravb: Fix NULL pointer access

[Marek Vasut]

On 9/20/20 9:34 AM, Biju Das wrote:

Hi,

[...]

>>> if we remove writephyext, by looking the code at [1], rxc-skew-ps will be
>> taken from the device tree[3] and "txc-skew-pc" will be the default
>> value(0xf).
>>> [3]https://elixir.bootlin.com/u-boot/v2020.10-rc4/source/arch/arm/dts/
>>> salvator-common.dtsi#L331
>>
>> So you want to check whether each RCar3 DT contains a PHY node and that
>> PHY node has rxc-skew-ps and txc-skew-ps , which combined then results
>> into a register value (0xf << 5) | (0x19 << 0) .
> 
> rxc-skew-ps set in DTS is 1500. 1 step is 60 ps, so 1500/60 = 25 which is 0x19 and this value will be overridden and stored in ofcfg->grp's val[0].

OK, good, thanks.

>>> I will check this and let you know the results after checking on RCar board.
>> Unfortunately currently I don't have RCar board.
>>
>> It's enough to just check the DTs and verify that they set the matching
>> correct values of rxc-skew-ps/txc-skew-ps . I can test it on the real hardware.
> 
> Yes, that way we can make sure the mapping operation is correct for this phy. 1500 in dts after mapping operation  should override
> ofcfg->grp's val[0] with 0x19.
> 
>> If you want, you can add the txc-skew-ps into the Linux R-Car3 DTs too.
> 
> We don't need to  set txc-skew-ps in dts, since it is same as default value and is filled in ofcfg->grp's val[1].
> We can avoid unnecessary mapping operations by not specifying in device tree, for default values.

Hopefully the default setting will not change in some new revision of
the PHY then.