From patchwork Tue Feb 1 00:18:10 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zev Weiss X-Patchwork-Id: 539156 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D7AB3C43219 for ; Tue, 1 Feb 2022 00:18:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229754AbiBAASt (ORCPT ); Mon, 31 Jan 2022 19:18:49 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60044 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230296AbiBAASs (ORCPT ); Mon, 31 Jan 2022 19:18:48 -0500 Received: from thorn.bewilderbeest.net (thorn.bewilderbeest.net [IPv6:2605:2700:0:5::4713:9cab]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CB8F0C06173B; Mon, 31 Jan 2022 16:18:48 -0800 (PST) Received: from hatter.bewilderbeest.net (174-21-190-118.tukw.qwest.net [174.21.190.118]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: zev) by thorn.bewilderbeest.net (Postfix) with ESMTPSA id EA9C9A6A; Mon, 31 Jan 2022 16:18:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bewilderbeest.net; s=thorn; t=1643674727; bh=GHTkxsASPABKmKkml1AsjQmWZbxD0ljM11iBp+9inDs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XerAaj0Rld0i0njCHB2mmNb+NdDJoITVLaTpFsJzm2/giAj+K077OduZ2AO0FOhu6 mN5pnLg732uoMUvFvy7p+ELJAnWGrOZdzT03Y/7oz0Vo6X/InFWmJFM/U+Gp7n9QAD eJfrtghgP4wj/eXJ61130Onw23wIqpY6bNBUvy/4= From: Zev Weiss To: linux-i2c@vger.kernel.org, Rob Herring , devicetree@vger.kernel.org Cc: Zev Weiss , openbmc@lists.ozlabs.org, linux-kernel@vger.kernel.org, Guenter Roeck , Peter Rosin 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> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220201001810.19516-1-zev@bewilderbeest.net> References: <20220201001810.19516-1-zev@bewilderbeest.net> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.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 Reviewed-by: Rob Herring --- 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>;