[PATCH 1/2] dt-bindings: firmware: arm,scmi: Document arm,poll-transport property

[Marek Vasut <marek.vasut+renesas@mailbox.org>]

Document new property arm,poll-transport, which sets all SCMI operation into
poll mode. This is meant to work around uncooperative SCP implementations,
which do not generate completion interrupts. This applies primarily on mbox
based implementations, but does also cover SMC and VirtIO ones.

With this property set, such implementations which do not generate interrupts
can be interacted with, until they are fixed to generate interrupts properly.

Note that, because the original base protocol exchange also requires some
sort of completion mechanism, it is not possible to query SCMI itself for
this property and it must be described in DT. While this does look a bit
like policy, the SCMI provider is part of the hardware, hence DT.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
---
Cc: Conor Dooley <conor+dt@kernel.org>
Cc: Cristian Marussi <cristian.marussi@arm.com>
Cc: Florian Fainelli <florian.fainelli@broadcom.com>
Cc: Krzysztof Kozlowski <krzk+dt@kernel.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: arm-scmi@vger.kernel.org
Cc: devicetree@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-renesas-soc@vger.kernel.org
---
 Documentation/devicetree/bindings/firmware/arm,scmi.yaml | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Documentation/devicetree/bindings/firmware/arm,scmi.yaml b/Documentation/devicetree/bindings/firmware/arm,scmi.yaml
index be817fd9cc34b..b53754a318ea1 100644
--- a/Documentation/devicetree/bindings/firmware/arm,scmi.yaml
+++ b/Documentation/devicetree/bindings/firmware/arm,scmi.yaml
@@ -146,6 +146,13 @@ properties:
       this platform. If set, the value should be non-zero.
     minimum: 1
 
+  arm,poll-transport:
+    type: boolean
+    description:
+      An optional property which unconditionally forces polling in all transports.
+      This is mainly mean to work around uncooperative SCP, which does not generate
+      completion interrupts.
+
   arm,smc-id:
     $ref: /schemas/types.yaml#/definitions/uint32
     description:
-- 
2.51.0