Thread (46 messages) 46 messages, 5 authors, 2025-12-11

Re: [PATCH 02/21] dt-bindings: display: tilcdc: Add fifo-threshold property

From: Kory Maincent <kory.maincent@bootlin.com>
Date: 2025-11-27 09:37:56
Also in: dri-devel, linux-devicetree, linux-omap, lkml

On Thu, 27 Nov 2025 09:22:56 +0100
Krzysztof Kozlowski [off-list ref] wrote:
On Wed, Nov 26, 2025 at 06:35:44PM +0100, Kory Maincent (TI.com) wrote:
quoted
Add the fifo-threshold property to control the DMA FIFO threshold level,
which specifies the number of words that must be loaded before the DMA
FIFO becomes ready.

This property is needed to support the da850-evm board configuration
which requires a non-default FIFO threshold value. Currently, this value
is specified through the deprecated ti,tilcdc,panel binding. Adding this
property to the tilcdc binding allows for proper configuration while
migrating away from the non-standard panel binding.

The default value is 8 words, with valid values being powers of 2 from
8 to 512.

Related commit: 55da73fa7a68c ("ARM: dts: davinci: da850-evm: Increase
fifo threshold")  
Please use syntax pointed out by checkpatch. The checkpatch error (not
even a warning) is there for reason, so we can apply filter/grep
easily.
quoted
Signed-off-by: Kory Maincent (TI.com) <kory.maincent@bootlin.com>
---
 Documentation/devicetree/bindings/display/tilcdc/tilcdc.yaml | 7 +++++++
 1 file changed, 7 insertions(+)
diff --git a/Documentation/devicetree/bindings/display/tilcdc/tilcdc.yaml
b/Documentation/devicetree/bindings/display/tilcdc/tilcdc.yaml index
34ac1fd04d5c6..bf6d506e25e17 100644 ---
a/Documentation/devicetree/bindings/display/tilcdc/tilcdc.yaml +++
b/Documentation/devicetree/bindings/display/tilcdc/tilcdc.yaml @@ -46,6
+46,13 @@ properties: The maximum pixel clock that can be supported by the
lcd controller in KHz.
 
+  fifo-threshold:  
Why this is not deducible from the compatible? Feels like a specific SoC
issue.
This is indeed deductible from the compatible as ti,da850-tilcdc is only use in
the related devicetree. Thanks for the pointer this will avoid adding a new dt
parameter.
Anyway, missing vendor prefix
quoted
+    $ref: /schemas/types.yaml#/definitions/uint32
+    enum: [8, 16, 32, 64, 128, 256, 512]
+    description:
+      Number of words loaded before the DMA fifo becomes ready. The default
+      value is 8.  
missing default and drop free form text in description.
quoted
+
   blue-and-red-wiring:
     enum: [straight, crossed]
     description:

-- 
2.43.0
  


-- 
Köry Maincent, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com
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