On Thu, May 14, 2020 at 11:35 AM Christophe Kerello <christophe.kerello@xxxxxx> wrote: > > Hi Rob, > > On 5/14/20 5:00 PM, Rob Herring wrote: > > On Wed, May 06, 2020 at 11:11:15AM +0200, Christophe Kerello wrote: > >> These bindings can be used on SOCs where the FMC2 NAND controller is > >> in standalone. In case that the FMC2 embeds 2 controllers (an external > >> bus controller and a raw NAND controller), the register base and the > >> clock will be defined in the parent node. It is the reason why the > >> register base address and the clock are now optional. > >> > >> Signed-off-by: Christophe Kerello <christophe.kerello@xxxxxx> > >> --- > >> .../devicetree/bindings/mtd/st,stm32-fmc2-nand.yaml | 19 ++++++++++--------- > >> 1 file changed, 10 insertions(+), 9 deletions(-) > >> > >> diff --git a/Documentation/devicetree/bindings/mtd/st,stm32-fmc2-nand.yaml b/Documentation/devicetree/bindings/mtd/st,stm32-fmc2-nand.yaml > >> index b059267..68fac1a 100644 > >> --- a/Documentation/devicetree/bindings/mtd/st,stm32-fmc2-nand.yaml > >> +++ b/Documentation/devicetree/bindings/mtd/st,stm32-fmc2-nand.yaml > >> @@ -18,13 +18,15 @@ properties: > >> > >> reg: > >> items: > >> - - description: Registers > >> + - description: Registers (optional) > > > > The only thing that can be optional are the last entries. You have to do > > a 'oneOf' with 6 entries and 7 entries. > > Ok, so the way to describe the reg property in my case should be: > reg: > oneOf: > - description: FMC2 embeds the NFC controller in standalone. > items: > - description: Registers > - description: Chip select 0 data > - description: Chip select 0 command > - description: Chip select 0 address space > - description: Chip select 1 data > - description: Chip select 1 command > - description: Chip select 1 address space > > - description: FMC2 embeds the NFC controller and the EBI > controller. > items: > - description: Chip select 0 data > - description: Chip select 0 command > - description: Chip select 0 address space > - description: Chip select 1 data > - description: Chip select 1 command > - description: Chip select 1 address space > > > > > And where's your new compatible string for this different h/w? > > From NFC controller point of view, it is the same HW. That's what everyone says until they have some quirk or integration difference to handle. > In the case that we have 2 controllers embedded, the register base is > shared. > The NFC driver will check at probe time the compatible string of its > parent node. > In case that it is "st,stm32mp1-fmc2-ebi", then the driver will find the > register base in the parent node (EBI node), otherwise it will find it > in the NFC node. > Is it better to have 2 compatible strings (one for each reg description) > than checking the parent's compatible string and have only one > compatible string? Why not just put the register base into the child node too? While overlapping 'reg' regions for siblings is bad, it's fine for child nodes. I guess since there are chip selects for the child nodes that may not work here. It doesn't hurt to have another compatible. You can always make the old one a fallback. With different compatibles you can make sure reg has the right number of entries. Rob
