Messages in this thread | | | Date | Mon, 10 Apr 2023 10:33:52 -0700 | Subject | Re: [PATCH 1/2] dt-bindings: firmware: arm,scmi: support parameter passing in smc/hvc | From | Nikunj Kela <> |
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On 4/10/2023 10:20 AM, Krzysztof Kozlowski wrote: > On 09/04/2023 20:19, Nikunj Kela wrote: >> Currently, smc/hvc calls are made with smc-id only. The parameters are >> all set to zeros. This patch defines two optional device tree bindings, >> that can be used to pass parameters in smc/hvc calls. >> >> This is useful when multiple scmi instances are used with common smc-id. >> >> Signed-off-by: Nikunj Kela <quic_nkela@quicinc.com> >> --- >> .../devicetree/bindings/firmware/arm,scmi.yaml | 16 ++++++++++++++++ >> 1 file changed, 16 insertions(+) >> >> diff --git a/Documentation/devicetree/bindings/firmware/arm,scmi.yaml b/Documentation/devicetree/bindings/firmware/arm,scmi.yaml >> index 5824c43e9893..08c331a79b80 100644 >> --- a/Documentation/devicetree/bindings/firmware/arm,scmi.yaml >> +++ b/Documentation/devicetree/bindings/firmware/arm,scmi.yaml >> @@ -115,6 +115,22 @@ properties: >> description: >> SMC id required when using smc or hvc transports >> >> + arm,smc32-params: >> + $ref: /schemas/types.yaml#/definitions/uint32-array >> + description: >> + An optional parameter list passed in smc32 or hvc32 calls >> + default: 0 >> + minItems: 1 >> + maxItems: 6 >> + >> + arm,smc64-params: >> + $ref: /schemas/types.yaml#/definitions/uint64-array >> + description: >> + An optional parameter list passed in smc64 or hvc64 calls >> + default: 0 >> + minItems: 1 >> + maxItems: 6 > These do not look like hardware properties and the fact that you need > two properties for the same also points that you tied it to specific SW > interface.
This is certainly not the H/W property but then smc-id is also not H/W property either
but that gets passed via DTB. I could use the same property for both however I wasn't sure
which datatype should be used, uint32-array/uint64-array. Moreover, I thought if users are
passing parameters, they better know which SMC convention they are using hence used two
explicit properties.
> Why this should be board-specific? Actually better question - why this > should be fixed per board? Doesn't my software want to have different > parameters, depending on some other condition?
Not sure I follow, I didn't say this is board specific. People can use the parameters to pass
whatever their S/W demands. SMC/HVC calls are made by passing parameters which is what this patch is enabling.
> > You also did not provide any DTS user for this, so difficult to judge > usefulness.
The work is still on going and we will push the dts in few months, however that shouldn't stop
making changes in advance.
> Best regards, > Krzysztof >
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