On 9/19/20 8:14 PM, Biju Das wrote: Hi,
[...] >>>>> By looking at [1], only this driver is using writeext. >>>>> [1]https://elixir.bootlin.com/u-boot/v2020.10-rc4/A/ident/writeext >>>> >>>> git grep indicates a couple more sites where the writeext is called. >>>> But look into the KSZ9031 datasheet, that particular writeext call >>>> seems to be setting up RGMII Clock Pad Skew (MMD Address 2, Register >>>> 8), and I think there is a matching DT binding to set those up too, >>>> rxc-skew-ps and txc- skew-ps I think. >>> >>> Thanks for the pointers. I checked the configs[2] which uses renesas >>> ravb driver and found that we are defining only rxc-skew-ps in all dts. >>> >>> since CONFIG DM_ETH is defined it is already picking the value >> corresponding to "rxc-skew-ps". >>> >>> For txc-skew-ps anyway the value is default one. So we don't care. >> >> Are you sure (0xf << 5) | 0x19 is the same as the default value of the clock >> pad skew register ? > > No. > As per [1] & [2], the default values for this registers are 0xf So the combined value of the MMD 2-8 register is (0xf << 5) | (0xf << 0) , right. > [1] > https://elixir.bootlin.com/u-boot/v2020.10-rc4/source/drivers/net/phy/micrel_ksz90x1.c#L105 > [2] http://ww1.microchip.com/downloads/en/devicedoc/00002117f.pdf > > 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) . > 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. If you want, you can add the txc-skew-ps into the Linux R-Car3 DTs too. btw unrelated, you seem to have rxc-skew-ps in your hihope-rzg2-ex.dtsi, but I think you don't have KSZ9031 PHY, so maybe you want to remove it form your DT too. Thanks
