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From: Zev Weiss <zev@bewilderbeest.net>
To: linux-i2c@vger.kernel.org, Rob Herring <robh+dt@kernel.org>,
 devicetree@vger.kernel.org
Subject: [PATCH v2 2/2] dt-bindings: i2c: add nxp,
 pca9541 release-delay-us property
Date: Mon, 31 Jan 2022 16:18:10 -0800
Message-Id: <20220201001810.19516-3-zev@bewilderbeest.net>
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Cc: openbmc@lists.ozlabs.org, Guenter Roeck <linux@roeck-us.net>,
 linux-kernel@vger.kernel.org, Zev Weiss <zev@bewilderbeest.net>,
 Peter Rosin <peda@axentia.se>
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 <openbmc-bounces+openbmc=archiver.kernel.org@lists.ozlabs.org>

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@bewilderbeest.net>
---
 Documentation/devicetree/bindings/i2c/nxp,pca9541.txt | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Documentation/devicetree/bindings/i2c/nxp,pca9541.txt b/Documentation/devicetree/bindings/i2c/nxp,pca9541.txt
index 42bfc09c8918..9e8819593271 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.
@@ -16,6 +24,7 @@ Example:
 	i2c-arbitrator@74 {
 		compatible = "nxp,pca9541";
 		reg = <0x74>;
+		release-delay-us = <20000>;
 
 		i2c-arb {
 			#address-cells = <1>;
-- 
2.34.1