Re: [PATCH v2 01/10] dt-bindings: mtd: brcmnand: Updates for bcmbca SoCs

[William Zhang]

Hi,

On 1/22/24 03:48, Jonas Gorski wrote:
> Hi,
>
> On Thu, 18 Jan 2024 at 20:56, <dregan@xxxxxxxxxxxx> wrote:
> > From: William Zhang <william.zhang@xxxxxxxxxxxx>
> >
> > Update the descriptions to reflect different families of broadband SoC and
> > use the general name bcmbca for ARM based SoC.
> >
> > Add brcm,nand-use-wp property to have an option for disabling this
> > feature on broadband board design that does not use write protection.
> >
> > Add brcm,nand-ecc-use-strap to get ecc setting from board boot strap for
> > broadband board designs because they do not specify ecc setting in dts
> > but rather using the strap setting.
> >
> > Remove the requirement of interrupts property to reflect the driver
> > code. Also add myself to the list of maintainers.
> >
> > Signed-off-by: William Zhang <william.zhang@xxxxxxxxxxxx>
> > Reviewed-by: David Regan <dregan@xxxxxxxxxxxx>
> > ---
> > Changes in v2:
> > - Revert the new compatible string nand-bcmbca
> > - Drop the BCM63168 compatible fix to avoid any potential ABI
> > incompatibility issue
> > - Simplify the explanation for brcm,nand-use-wp
> > - Keep the interrupt name requirement when interrupt number is specified
> > ---
> >   .../bindings/mtd/brcm,brcmnand.yaml           | 36 +++++++++++++++----
> >   1 file changed, 30 insertions(+), 6 deletions(-)
> >
> > diff --git a/Documentation/devicetree/bindings/mtd/brcm,brcmnand.yaml b/Documentation/devicetree/bindings/mtd/brcm,brcmnand.yaml
> > index f57e96374e67..56176ec1a992 100644
> > --- a/Documentation/devicetree/bindings/mtd/brcm,brcmnand.yaml
> > +++ b/Documentation/devicetree/bindings/mtd/brcm,brcmnand.yaml
> > @@ -9,6 +9,7 @@ title: Broadcom STB NAND Controller
> >   maintainers:
> >     - Brian Norris <computersforpeace@xxxxxxxxx>
> >     - Kamal Dasu <kdasu.kdev@xxxxxxxxx>
> > +  - William Zhang <william.zhang@xxxxxxxxxxxx>
> >
> >   description: |
> >     The Broadcom Set-Top Box NAND controller supports low-level access to raw NAND
> > @@ -18,9 +19,10 @@ description: |
> >     supports basic PROGRAM and READ functions, among other features.
> >
> >     This controller was originally designed for STB SoCs (BCM7xxx) but is now
> > -  available on a variety of Broadcom SoCs, including some BCM3xxx, BCM63xx, and
> > -  iProc/Cygnus. Its history includes several similar (but not fully register
> > -  compatible) versions.
> > +  available on a variety of Broadcom SoCs, including some BCM3xxx, MIPS based
> > +  Broadband SoC (BCM63xx), ARM based Broadband SoC (BCMBCA) and iProc/Cygnus.
> > +  Its history includes several similar (but not fully register compatible)
> > +  versions.
> >
> >     -- Additional SoC-specific NAND controller properties --
> >
> > @@ -53,7 +55,7 @@ properties:
> >                 - brcm,brcmnand-v7.2
> >                 - brcm,brcmnand-v7.3
> >             - const: brcm,brcmnand
> > -      - description: BCM63138 SoC-specific NAND controller
> > +      - description: BCMBCA SoC-specific NAND controller
> >           items:
> >             - const: brcm,nand-bcm63138
> >             - enum:
> > @@ -65,7 +67,7 @@ properties:
> >             - const: brcm,nand-iproc
> >             - const: brcm,brcmnand-v6.1
> >             - const: brcm,brcmnand
> > -      - description: BCM63168 SoC-specific NAND controller
> > +      - description: BCM63xx SoC-specific NAND controller
>
> Only the BCM63268 family has a v4.0 NAND controller with support for
> ONFI and raw access; BCM6368 has a v2.1, and BCM6328 and BCM6362 have
> a v2.2.
>
> So claiming this is a generic binding is wrong; you would need to add
> the appropriate variants first. Or add another one for the BCM6368
> NAND v2.x controllers, which is missing. You can find them used in
> arch/mips/boot/dts/brcm/bcm63{28,62,68}.dtsi.
I am not changing binding here but jsut update the description to 
identify these MIPS based chip as bcm63xx family. This convention is 
used in other IP blocks too.  And yes this binding is not correct and I 
noticed the same v2.x usage in the dtsi files you pointed out. So I 
actually updated this binding in my v1 here
https://lore.kernel.org/lkml/20230606231252.94838-6-william.zhang@xxxxxxxxxxxx/
but there was some concern as it could possibly break the ABI in that 
thread's discussion.

So I decided to take that change off this patch series since it is not 
related to my change (ARM based BCMBCA family) either. It should be a 
separate patch to address this MIPS based SoCs binding issue.
> >           items:
> >             - const: brcm,nand-bcm63168
> >             - const: brcm,nand-bcm6368
>
> Also bcm63168's v4.0 has a different register layout than bcm6368's
> v2.x, so claiming brcm.nand-bcm6368 as compatible here is a bit weird.
> It works because the register layout used is derived from the
> "brcm,brcmnand-vX.Y" compatible, and the driver attaching to
> 'brcm,nand-bcm6368" only uses the shared interrupt registers which are
> identical, the layout only diverges after that.
>
> But then again these aren't really used as compatibles in the original
> sense, and more like tags which describe different parts of the
> controller, and the combination is the whole unique "compatible". Not
> sure if this is how compatibles are supposed to be used. /rant.
>
> Best Regards,
> Jonas

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