[PATCH] dt-bindings: misc: add documentation for Xilinx AXI-Stream FIFO IP core

[PATCH] dt-bindings: misc: add documentation for Xilinx AXI-Stream FIFO IP core

[Kartik Nair]

Add device tree binding documentation for the Xilinx AXI-Stream FIFO
IP core (PG080). This documents the compatible strings used in
drivers/staging/axis-fifo/axis-fifo.c which were previously flagged
as undocumented by checkpatch.

Documented compatible strings:
- xlnx,axi-fifo-mm-s-4.1
- xlnx,axi-fifo-mm-s-4.2
- xlnx,axi-fifo-mm-s-4.3

Signed-off-by: Kartik Nair <contact.kartikn@gmail.com>
---
 .../bindings/misc/xlnx,axi-fifo-mm-s.yaml     | 44 +++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/misc/xlnx,axi-fifo-mm-s.yaml

diff --git a/Documentation/devicetree/bindings/misc/xlnx,axi-fifo-mm-s.yaml b/Documentation/devicetree/bindings/misc/xlnx,axi-fifo-mm-s.yaml
new file mode 100644
index 000000000..597699034
--- /dev/null
+++ b/Documentation/devicetree/bindings/misc/xlnx,axi-fifo-mm-s.yaml
@@ -0,0 +1,44 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/misc/xlnx,axi-fifo-mm-s.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Xilinx AXI-Stream FIFO IP Core
+
+maintainers:
+  - Jacob Feder <jacobsfeder@gmail.com>
+
+description:
+  The Xilinx AXI-Stream FIFO IP core allows memory-mapped access to an
+  AXI-Stream interface. It supports both transmit and receive FIFO
+  operations via a memory-mapped register interface. See Xilinx PG080
+  for full IP details.
+
+properties:
+  compatible:
+    enum:
+      - xlnx,axi-fifo-mm-s-4.1
+      - xlnx,axi-fifo-mm-s-4.2
+      - xlnx,axi-fifo-mm-s-4.3
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - interrupts
+
+additionalProperties: false
+
+examples:
+  - |
+    axi_fifo: fifo@43c00000 {
+        compatible = "xlnx,axi-fifo-mm-s-4.1";
+        reg = <0x43c00000 0x10000>;
+        interrupts = <0 58 4>;
+    };
-- 
2.50.0

Re: [PATCH] dt-bindings: misc: add documentation for Xilinx AXI-Stream FIFO IP core

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [High] The YAML binding schema is incomplete and sets `additionalProperties: false`, which rejects valid device trees and breaks driver probing.
- [Low] The commit introduces a new YAML binding but fails to remove the existing text-based binding, leading to duplicated and conflicting documentation.
--

commit a25eb1af928bc942c4ddef43a8d5e91efa619819
Author: Kartik Nair <contact.kartikn@gmail.com>

dt-bindings: misc: add documentation for Xilinx AXI-Stream FIFO IP core

This patch adds device tree binding documentation for the Xilinx AXI-Stream
FIFO IP core. It introduces a new YAML schema to document the compatible
strings used by the axis-fifo driver.

Does this update also need to remove the existing text-based binding at
drivers/staging/axis-fifo/axis-fifo.txt? Keeping the legacy text file
alongside the new YAML schema introduces duplicated and conflicting
documentation.

> diff --git a/Documentation/devicetree/bindings/misc/xlnx,axi-fifo-mm-s.yaml b/Documentation/devicetree/bindings/misc/xlnx,axi-fifo-mm-s.yaml
> new file mode 100644
> index 0000000000000..597699034f134
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/misc/xlnx,axi-fifo-mm-s.yaml
> @@ -0,0 +1,44 @@
[ ... ]
> +properties:
> +  compatible:
> +    enum:
> +      - xlnx,axi-fifo-mm-s-4.1
> +      - xlnx,axi-fifo-mm-s-4.2
> +      - xlnx,axi-fifo-mm-s-4.3
> +
> +  reg:
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1

The drivers/staging/axis-fifo/axis-fifo.c driver requires several vendor
specific properties to probe successfully, such as
xlnx,axi-str-rxd-tdata-width, xlnx,axi-str-txd-tdata-width,
xlnx,rx-fifo-depth, xlnx,tx-fifo-depth, xlnx,use-rx-data, and
xlnx,use-tx-data.

Are these properties missing from the schema?

> +required:
> +  - compatible
> +  - reg
> +  - interrupts
> +
> +additionalProperties: false

If the vendor properties are added to the device tree to allow the driver
to probe, won't setting additionalProperties to false cause the schema
validation to fail?

Device trees that pass this strict schema would then fail at runtime since
the driver will abort the probe when the missing properties are not found.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260510190908.400-1-contact.kartikn@gmail.com?part=1