From patchwork Tue Apr 5 12:16:26 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vincent Whitchurch X-Patchwork-Id: 1613462 Return-Path: X-Original-To: incoming-dt@patchwork.ozlabs.org Delivered-To: patchwork-incoming-dt@bilbo.ozlabs.org Authentication-Results: bilbo.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=axis.com header.i=@axis.com header.a=rsa-sha256 header.s=axis-central1 header.b=ae7dSkD7; dkim-atps=neutral Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=2620:137:e000::1:20; helo=out1.vger.email; envelope-from=devicetree-owner@vger.kernel.org; receiver=) Received: from out1.vger.email (out1.vger.email [IPv6:2620:137:e000::1:20]) by bilbo.ozlabs.org (Postfix) with ESMTP id 4KXqBD2GZbz9sBJ for ; Wed, 6 Apr 2022 00:03:48 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242722AbiDEN7E (ORCPT ); Tue, 5 Apr 2022 09:59:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53350 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1380267AbiDENOA (ORCPT ); Tue, 5 Apr 2022 09:14:00 -0400 Received: from smtp2.axis.com (smtp2.axis.com [195.60.68.18]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 307D312343F; Tue, 5 Apr 2022 05:16:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=axis.com; q=dns/txt; s=axis-central1; t=1649160997; x=1680696997; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=IQbFdsIycaKMPC2WtqAU6bZcJ0n+YEHMU/Uu+zlGT7I=; b=ae7dSkD7GoCDc2NTaNCq3XgDrTcm4p7/80S49gpON3AX+mYkUIK84gnr jnK5D2akK5XnMwxmSBJSt231FFA755yUKQmY1aQUTnPi9SeTtJHyHSeH6 oGk/xBHyVyz1j12hQ7Xp41SzTa4gGfwUDk4nfaHC+xxEfhzwM2A7ypP6T 6wdpGzTOU+WO5QoCummNdb2bJR8dtJBVNjeRYBNMFuJ6VEpDF8P/yP8We qLCVY+WiFMpZq2DdG73QIP4oDnbwP9A56lVtoP0WpqP3jcnKcndsP7d01 R4wu1f2NXr88o+GsfnvzlQRc6npEroX8psnY3nyn8gyebdVTuznsxNq+T Q==; From: Vincent Whitchurch To: CC: , Vincent Whitchurch , , , , , Subject: [PATCH 1/2] i2c: add binding to prevent device detection Date: Tue, 5 Apr 2022 14:16:26 +0200 Message-ID: <20220405121627.1560949-2-vincent.whitchurch@axis.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220405121627.1560949-1-vincent.whitchurch@axis.com> References: <20220405121627.1560949-1-vincent.whitchurch@axis.com> MIME-Version: 1.0 X-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED,SPF_HELO_PASS, SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org When drivers with ->detect callbacks are loaded, the I2C core does a bunch of transactions to try to probe for these devices, regardless of whether they are specified in the devicetree or not. (This only happens on I2C controllers whose drivers enable the I2C_CLASS* flags, but this is the case for generic drivers like i2c-gpio.) These kinds of transactions are unnecessary on systems where the devicetree specifies all the devices on the I2C bus, so add a property to allow them to be disabled. Signed-off-by: Vincent Whitchurch --- Documentation/devicetree/bindings/i2c/i2c.txt | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/Documentation/devicetree/bindings/i2c/i2c.txt b/Documentation/devicetree/bindings/i2c/i2c.txt index fc3dd7ec0445..5f7bdf4851e8 100644 --- a/Documentation/devicetree/bindings/i2c/i2c.txt +++ b/Documentation/devicetree/bindings/i2c/i2c.txt @@ -72,6 +72,10 @@ wants to support one of the below features, it should adapt these bindings. this information to adapt power management to keep the arbitration awake all the time, for example. Can not be combined with 'single-master'. +- no-detect + states that the system should not attempt to automatically detect + devices which are not explicitly specified as child nodes. + - pinctrl add extra pinctrl to configure SCL/SDA pins to GPIO function for bus recovery, call it "gpio" or "recovery" (deprecated) state