From patchwork Mon Jan 24 21:38:50 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zev Weiss X-Patchwork-Id: 536967 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 D44EAC43219 for ; Tue, 25 Jan 2022 02:18:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1357643AbiAYCSm (ORCPT ); Mon, 24 Jan 2022 21:18:42 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57282 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2364012AbiAXXqc (ORCPT ); Mon, 24 Jan 2022 18:46:32 -0500 Received: from thorn.bewilderbeest.net (thorn.bewilderbeest.net [IPv6:2605:2700:0:5::4713:9cab]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2BBE9C034006; Mon, 24 Jan 2022 13:41:26 -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 7EF76690; Mon, 24 Jan 2022 13:39:02 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bewilderbeest.net; s=thorn; t=1643060342; bh=DqrmV9MGxyAiCEmRUewAEVdQrxV9eeYb1sRoUnPeamw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=IXBCUJKGE9YD/G80hJhY8Kfm2oTJoQuw5vq/kkdy2/kzNIVKnIlndgJziGn2ncHbk PAFjxjq/BPYcA8gz2fpD5HIMaa8rE0WRHXsWiKFiEDHECiOowH7X8CLC9hDaIOW+BZ 6I0+4++DX2p/byi0oKBhTugMvf5sAqNDz133JjtU= 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 2/2] dt-bindings: i2c: add nxp,pca9541 release-delay-us property Date: Mon, 24 Jan 2022 13:38:50 -0800 Message-Id: <20220124213850.3766-3-zev@bewilderbeest.net> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220124213850.3766-1-zev@bewilderbeest.net> References: <20220124213850.3766-1-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 --- 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 i2c-arbitrator@74 { compatible = "nxp,pca9541"; reg = <0x74>; + release-delay-us = <20000>; i2c-arb { #address-cells = <1>;