Re: [PATCH 2/2] dt-bindings: nand: Add Cadence NAND controller driver

[Piotr Sroka]

The 01/29/2019 18:21, Boris Brezillon wrote:
 
> > +Optional properties:
> > +Driver calculates controller timings base on NAND flash memory timings and
> > +the following delays in picoseconds.
> > +  - cdns,if-skew : Skew value of the output signals of the NAND Flash interface
> > +  - cdns,nand2-delay : Delay value of one NAND2 gate from which
> > +    the delay element is build
> > +  - cdns,board-delay : Estimated Board delay. The value includes the total
> > +    round trip delay for the signals and is used for deciding on values
> > +    associated with data read capture. The example formula for SDR mode is
> > +    the following:
> > +    board_delay = RE#PAD_delay + PCB trace to device + PCB trace from device
> > +    + DQ PAD delay
>
> The unit of those props is not defined, and if possible I'd like to
> avoid specifying custom timing adjustment values in the DT. Looks like
> some of these values are SoC specific (depends on the integration of
> this IP in a SoC) and others are board specific. For SoC specific
> values, this should be attached to the SoC specific compatible at the
> driver level. For board-specific values, I'd prefer to have a generic
> way to describe boards constraints.
Moving SoC specific delays from DTS to the driver data is clear for me. I do not know how to handle a board delay. Could you give me an example how it may be implemented? Where this board related stuff could be placed?

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Regards
Piotr Sroka