Hi Rob,
On 5/14/20 7:55 PM, Rob Herring wrote:
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
I will add a new compatible string to handle the reg property.
It will be part of v5.
Regards,
Christophe Kerello.
