Hi Rob, miquel.raynal@xxxxxxxxxxx wrote on Thu, 16 Dec 2021 16:02:26 +0100: > Hi Rob, > > robh@xxxxxxxxxx wrote on Tue, 14 Dec 2021 11:32:56 -0600: > > > On Fri, Dec 10, 2021 at 09:10:38PM +0100, Miquel Raynal wrote: > > > Describe two new memories modes: > > > - A stacked mode when the bus is common but the address space extended > > > with an additinals wires. > > > - A parallel mode with parallel busses accessing parallel flashes where > > > the data is spread. > > > > > > Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx> > > > --- > > > .../bindings/spi/spi-peripheral-props.yaml | 29 +++++++++++++++++++ > > > 1 file changed, 29 insertions(+) > > > > > > diff --git a/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml b/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml > > > index 5dd209206e88..4194fee8f556 100644 > > > --- a/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml > > > +++ b/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml > > > @@ -82,6 +82,35 @@ properties: > > > description: > > > Delay, in microseconds, after a write transfer. > > > > > > + stacked-memories: > > > + $ref: /schemas/types.yaml#/definitions/uint64-matrix > > > > matrix or... > > > > > + description: Several SPI memories can be wired in stacked mode. > > > + This basically means that either a device features several chip > > > + selects, or that different devices must be seen as a single > > > + bigger chip. This basically doubles (or more) the total address > > > + space with only a single additional wire, while still needing > > > + to repeat the commands when crossing a chip boundary. The size of > > > + each chip should be provided as members of the array. > > > > array? > > > > Sounds like an array from the description as there is only 1 element, > > the size. > > Well, what I expected to have was something like: > > dt: <property> = <uint64>, <uint64>; > > It seemed like the only possible way (that the tooling would validate) > was to use: > > bindings: $ref: /schemas/types.yaml#/definitions/uint64-matrix > > So I assumed I was defining a matrix of AxB elements, where A is the > number of devices I want to "stack" and B is the number of values > needed to describe its size, so 1. > > I realized that the following example, which I was expecting to work, > was failing: > > bindings: $ref: /schemas/types.yaml#/definitions/uint64-array > dt: <property> = <uint64>, <uint64>; > > Indeed, as you propose, this actually works but describes two values > (tied somehow) into a single element, which is not exactly what I > wanted: > > bindings: $ref: /schemas/types.yaml#/definitions/uint64-array > dt: <property> = <uint64 uint64>; > > But more disturbing, all the following constructions worked, when using > 32-bits values instead: > > bindings: $ref: /schemas/types.yaml#/definitions/uint32-array > dt: <property> = <uint32 uint32>; > > bindings: $ref: /schemas/types.yaml#/definitions/uint32-array > dt: <property> = <uint32>, <uint32>; > > bindings: $ref: /schemas/types.yaml#/definitions/uint32-matrix > dt: <property> = <uint32 uint32>; > > bindings: $ref: /schemas/types.yaml#/definitions/uint32-matrix > dt: <property> = <uint32>, <uint32>; > > I am fine waiting a bit if you think there is a need for some tooling > update on your side. Otherwise, do you really think that this solution > is the one we should really use? > > bindings: $ref: /schemas/types.yaml#/definitions/uint64-array > dt: <property> = <uint64 uint64>; > > Because from my point of view it does not match what we usually do for > other "types" of elements, such as: > > dt: <property> = <phandle1 index1>, <phandle2 index2>; > > or > > dt: <property> = <small-val1>, <small-val2>; Sorry for bothering you, is this something you still have in mind? It seems that the tooling is the culprit here and I would highly appreciate your help on that point. Thanks, Miquèl > > > > > > + minItems: 2 > > > + maxItems: 2 > > > + items: > > > + maxItems: 1 > > > > This says you can only have 2 64-bit entries. Probably not what you > > want. This looks like a case for a maxItems 'should be enough for now' > > type of value. > > Yes, that is what I wanted to describe. > > In my recent contributions you always preferred to bound things as much > as possible, even though later it might become necessary to loosen the > constraint. Right now I see the use of these properties for 2 devices, > but in theory there is no limit. > > Of course if we switch to the array representation I suppose I should > stick to: > > + minItems: 2 > + maxItems: 2
