Re: [RFC PATCH v2 1/2] dt-bindings: nand: meson: support for 512B ECC step size

[Miquel Raynal <miquel.raynal@bootlin.com>]

Hi Arseniy,

avkrasnov@sberdevices.ru wrote on Wed, 5 Jul 2023 11:03:30 +0300:

> On 05.07.2023 10:37, Miquel Raynal wrote:
> > Hi Arseniy,
> > 
> > AVKrasnov@sberdevices.ru wrote on Wed, 5 Jul 2023 09:54:33 +0300:
> >   
> >> Meson NAND supports both 512B and 1024B ECC step size, so replace
> >> 'const' for only 1024B step size with enum for both sizes.
> >>
> >> Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
> >> ---
> >>  Documentation/devicetree/bindings/mtd/amlogic,meson-nand.yaml | 4 +++-
> >>  1 file changed, 3 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/Documentation/devicetree/bindings/mtd/amlogic,meson-nand.yaml b/Documentation/devicetree/bindings/mtd/amlogic,meson-nand.yaml
> >> index 3bec8af91bbb..81ca8828731a 100644
> >> --- a/Documentation/devicetree/bindings/mtd/amlogic,meson-nand.yaml
> >> +++ b/Documentation/devicetree/bindings/mtd/amlogic,meson-nand.yaml
> >> @@ -49,7 +49,8 @@ patternProperties:
> >>          const: hw
> >>  
> >>        nand-ecc-step-size:
> >> -        const: 1024
> >> +        enum: [512, 1024]
> >> +        default: 1024  
> > 
> > I was actually wrong in my previous review, there is no strong default
> > here as the existing binding (and code) try to use the closest
> > parameters required by the NAND chip: we pick the "optimal"
> > configuration. So if you don't provide any value here, we expect
> > the strength and step size advertized by the chip to be used. This is a
> > common default in the raw NAND subsystem.
> > 
> > Please drop the default line, re-integrate the missing R-by tag from
> > Rob and in a separate patch please mark nand-ecc-step-size and
> > nand-ecc-strength mandatory if the other is provide. IOW, we expect
> > either both, or none of them, but not a single one.  
> 
> I see, no problem! "mandatory" means update description of both fields like:
> 
>     description:                                                        
>       Mandatory if nand-ecc-step-size is set.

Nope :-)

Something along:

allOf:
  - if:
    <nand-chip>:
      properties:
        contains:
          - nand-ecc-step-size
    then:
      required:
        <nand-chip>:
          properties:
            - nand-ecc-strength

And same with the opposite logic.

> 
> etc.
> 
> ?
> 
> >   
> >>  
> >>        nand-ecc-strength:
> >>          enum: [8, 16, 24, 30, 40, 50, 60]
> >> @@ -93,6 +94,7 @@ examples:
> >>        nand@0 {
> >>          reg = <0>;
> >>          nand-rb = <0>;
> >> +        nand-ecc-step-size = <1024>;  
> > 
> > So in the end this line is wrong and once you get the description right
> > as I mentioned it above, this will fail to pass
> > `make DT_SCHEMA_FILES=Documentation/devicetree/bindings/mtd/ dt_binidng_check`
> > Please drop it from the example, don't add the second property here,
> > it's best to show a clean example where people stop tampering for no
> > reason with the optimal values.  
> 
> Ok!
> 
> Thanks, Arseniy
> 
> >   
> >>        };
> >>      };
> >>    
> > 
> > 
> > Thanks,
> > Miquèl  


Thanks,
Miquèl