[PATCH 1/2] spi: dt-bindings: introduce linux,use-rt-queue flag

[Matthias Schiffer <matthias.schiffer@xxxxxxxxxxxxxxx>]

We have seen a number of downstream patches that allow enabling the
realtime feature of the SPI subsystem to reduce latency. These were
usually implemented for a specific SPI driver, even though the actual
handling of the rt flag is happening in the generic SPI controller code.

Introduce a generic linux,use-rt-queue flag that can be used with any
controller driver. The now redundant driver-specific pl022,rt flag is
marked as deprecated.

Signed-off-by: Matthias Schiffer <matthias.schiffer@xxxxxxxxxxxxxxx>
---
 Documentation/devicetree/bindings/spi/spi-controller.yaml | 6 ++++++
 Documentation/devicetree/bindings/spi/spi-pl022.yaml      | 4 +++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/spi/spi-controller.yaml b/Documentation/devicetree/bindings/spi/spi-controller.yaml
index 524f6fe8c27b4..a24b4ea87443b 100644
--- a/Documentation/devicetree/bindings/spi/spi-controller.yaml
+++ b/Documentation/devicetree/bindings/spi/spi-controller.yaml
@@ -79,6 +79,12 @@ properties:
     description:
       The SPI controller acts as a slave, instead of a master.
 
+  linux,use-rt-queue:
+    $ref: /schemas/types.yaml#/definitions/flag
+    description:
+      Indicates that the controller should run the message pump with realtime
+      priority to minimise the transfer latency on the bus.
+
   slave:
     type: object
 
diff --git a/Documentation/devicetree/bindings/spi/spi-pl022.yaml b/Documentation/devicetree/bindings/spi/spi-pl022.yaml
index 91e540a92fafe..3c43fcc007e1f 100644
--- a/Documentation/devicetree/bindings/spi/spi-pl022.yaml
+++ b/Documentation/devicetree/bindings/spi/spi-pl022.yaml
@@ -49,8 +49,10 @@ properties:
 
   pl022,rt:
     description: indicates the controller should run the message pump with realtime
-      priority to minimise the transfer latency on the bus (boolean)
+      priority to minimise the transfer latency on the bus (deprecated, use the
+      generic linux,use-rt-queue property)
     type: boolean
+    deprecated: true
 
   dmas:
     description:
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