linux-kernel - [PATCH 2/2] dt-bindings: i2c: add nxp,pca9541 release-delay-us property

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Message-Id: <20220124213850.3766-3-zev@bewilderbeest.net>
Date:   Mon, 24 Jan 2022 13:38:50 -0800
From:   Zev Weiss <zev@...ilderbeest.net>
To:     linux-i2c@...r.kernel.org, Rob Herring <robh+dt@...nel.org>,
        devicetree@...r.kernel.org
Cc:     Zev Weiss <zev@...ilderbeest.net>, openbmc@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org, Guenter Roeck <linux@...ck-us.net>,
        Peter Rosin <peda@...ntia.se>
Subject: [PATCH 2/2] dt-bindings: i2c: add nxp,pca9541 release-delay-us property

This property can be used to reduce arbitration overhead on busy i2c
busses by retaining ownership for a brief period in anticipation of
another transaction in the near future.

Signed-off-by: Zev Weiss <zev@...ilderbeest.net>
---
 Documentation/devicetree/bindings/i2c/nxp,pca9541.txt | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Documentation/devicetree/bindings/i2c/nxp,pca9541.txt b/Documentation/devicetree/bindings/i2c/nxp,pca9541.txt
index 42bfc09c8918..c755da59d6ec 100644
--- a/Documentation/devicetree/bindings/i2c/nxp,pca9541.txt
+++ b/Documentation/devicetree/bindings/i2c/nxp,pca9541.txt
@@ -6,6 +6,14 @@ Required Properties:
 
   - reg: The I2C address of the device.
 
+Optional Properties:
+
+ - release-delay-us: the number of microseconds to delay before
+   releasing the bus after a transaction.  If unspecified the default
+   is zero (the bus is released immediately).  Non-zero values can
+   reduce arbitration overhead for back-to-back transactions, at the
+   cost of delaying the other master's access to the bus.
+
   The following required properties are defined externally:
 
   - I2C arbitration bus node. See i2c-arb.txt in this directory.
@@ -13,9 +21,11 @@ Required Properties:
 
 Example:
 
+	#include <dt-bindings/mux/mux.h>
 	i2c-arbitrator@74 {
 		compatible = "nxp,pca9541";
 		reg = <0x74>;
+		release-delay-us = <20000>;
 
 		i2c-arb {
 			#address-cells = <1>;
-- 
2.34.1