Re: 回覆: 回覆: [net-next 4/4] net: ftgmac100: add RGMII delay for AST2600

[Andrew Lunn]

On Tue, Mar 18, 2025 at 05:34:08AM +0000, Jacky Chou wrote:
> Hi Andrew,
> 
> Thank you for your reply.
> 
> > > The RGMII delay of AST2600 has a lot of steps can be configured.
> > 
> > Are they uniformly space? Then it should be a simple formula to calculate? Or
> > a lookup table?
> 
> There are fixed delay values by step. I list below.
> AST2600 MAC0/1 one step delay = 45 ps
> AST2600 MAC2/3 one step delay = 250 ps

That is messy.

> I calculate all step and emulate them.
> The dt-binding will be like below.
> rx-internal-delay-ps:
>     description:
>       Setting this property to a non-zero number sets the RX internal delay
>       for the MAC. ... skip ...
>     enum:
>       [45, 90, 135, 180, 225, 250, 270, 315, 360, 405, 450, 495, 500, 540, 585, 630, 675, 
>        720, 750, 765, 810, 855, 900, 945, 990, 1000, 1035, 1080, 1125, 1170, 1215, 1250, 
>        1260, 1305, 1350, 1395, 1440, 1500, 1750, 2000, 2250, 2500, 2750, 3000, 3250, 3500, 
>        3750, 4000, 4250, 4500, 4750, 5000, 5250, 5500, 5750, 6000, 6250, 6500, 6750, 7000, 
>        7250, 7500, 7750, 8000]

Can the hardware do 0 ps?

So this list is a superset of both 45ps and 250ps steps?

Lets see what the DT Maintainers say, but it could be you need two
different compatibles for mac0/1 to mac2/3 because they are not
actually compatible! You can then have a list per compatible.

	Andrew