From patchwork Mon Jan 24 21:38:48 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zev Weiss X-Patchwork-Id: 536668 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 ACFEEC4321E for ; Tue, 25 Jan 2022 02:18:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S3410236AbiAYCSl (ORCPT ); Mon, 24 Jan 2022 21:18:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57256 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2363959AbiAXXq1 (ORCPT ); Mon, 24 Jan 2022 18:46:27 -0500 X-Greylist: delayed 137 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Mon, 24 Jan 2022 13:41:19 PST Received: from thorn.bewilderbeest.net (thorn.bewilderbeest.net [IPv6:2605:2700:0:5::4713:9cab]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EC4CAC0417C0; Mon, 24 Jan 2022 13:41:19 -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 D963B1E6; Mon, 24 Jan 2022 13:39:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bewilderbeest.net; s=thorn; t=1643060342; bh=6xNUxjEcpAPXQtqj2dw1JnrsCyGZcDtUqq17fYGSuBI=; h=From:To:Cc:Subject:Date:From; b=pDmSmp2iDp20Bo3XfxuH1oDIeCI9ZF3F5yxRmW/4n42hZFQy8/EYtZryCCFfTwpu/ jcdtrgLDBgM0PDv+h5pfjwB+0IuqWbmE+qZu41AylxmfJ7cCUJt6lkND1ELOODghQO cGEIDur1gXxmukKNKkhtEa648nStcWHEpwPzUAT0= From: Zev Weiss To: linux-i2c@vger.kernel.org, Guenter Roeck , Peter Rosin , Rob Herring Cc: Zev Weiss , openbmc@lists.ozlabs.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org Subject: [PATCH 0/2] ic2: mux: pca9541: add delayed-release support Date: Mon, 24 Jan 2022 13:38:48 -0800 Message-Id: <20220124213850.3766-1-zev@bewilderbeest.net> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org Hello, This series adds support for a new pca9541 device-tree property ("release-delay-us"), which delays releasing ownership of the bus after a transaction for a configurable duration, anticipating that another transaction may follow shortly. By avoiding a release/reacquisition between transactions, this can provide a substantial performance improvement for back-to-back operations -- on a Delta AHE-50DC (ASPEED AST1250) system running OpenBMC with LM25066 PMICs behind PCA9541-arbitrated busses, a setting of 10000 (10 ms) reduces the median latency of reading hwmon sysfs files from 2.28 ms to 0.99 ms (a 57% improvement). Thanks, Zev Zev Weiss (2): i2c: mux: pca9541: add delayed-release support dt-bindings: i2c: add nxp,pca9541 release-delay-us property .../devicetree/bindings/i2c/nxp,pca9541.txt | 10 ++++ drivers/i2c/muxes/i2c-mux-pca9541.c | 56 ++++++++++++++++--- 2 files changed, 57 insertions(+), 9 deletions(-)