From mboxrd@z Thu Jan 1 00:00:00 1970 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 D4EE3C433EF for ; Mon, 7 Mar 2022 10:03:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239911AbiCGKD4 (ORCPT ); Mon, 7 Mar 2022 05:03:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35352 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240498AbiCGKBE (ORCPT ); Mon, 7 Mar 2022 05:01:04 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B4365BC84; Mon, 7 Mar 2022 01:49:17 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 70B27B810A8; Mon, 7 Mar 2022 09:49:16 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D7BA4C340F5; Mon, 7 Mar 2022 09:49:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1646646555; bh=YfYYgfEG/tUw+RF/Z5+2ChlPUubhZWSVdHx6WExWyhs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=iUH2Ak3L64nYnUC4klM5xorHFAWsYggIbhxpsjZ9ec3nKuOHJgBSOUSCu4BwaJnqU DBXUFUFun+3EzJAWpTAgYOUBnAiqlb2dM5Erat6D0fs/b9bJzpPiMmLbNvQxRyw6Zq 0Dca2ktiG145+7+ETFl1db1f8BHnO3RIko2QgIOo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Anholt , Stefan Wahren , Wolfram Sang , Sasha Levin Subject: [PATCH 5.16 003/186] i2c: bcm2835: Avoid clock stretching timeouts Date: Mon, 7 Mar 2022 10:17:21 +0100 Message-Id: <20220307091654.191826097@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220307091654.092878898@linuxfoundation.org> References: <20220307091654.092878898@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Eric Anholt [ Upstream commit 9495b9b31abe525ebd93da58de2c88b9f66d3a0e ] The CLKT register contains at poweron 0x40, which at our typical 100kHz bus rate means .64ms. But there is no specified limit to how long devices should be able to stretch the clocks, so just disable the timeout. We still have a timeout wrapping the entire transfer. Signed-off-by: Eric Anholt Signed-off-by: Stefan Wahren BugLink: https://github.com/raspberrypi/linux/issues/3064 Signed-off-by: Wolfram Sang Signed-off-by: Sasha Levin --- drivers/i2c/busses/i2c-bcm2835.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/i2c/busses/i2c-bcm2835.c b/drivers/i2c/busses/i2c-bcm2835.c index 37443edbf7546..ad3b124a2e376 100644 --- a/drivers/i2c/busses/i2c-bcm2835.c +++ b/drivers/i2c/busses/i2c-bcm2835.c @@ -23,6 +23,11 @@ #define BCM2835_I2C_FIFO 0x10 #define BCM2835_I2C_DIV 0x14 #define BCM2835_I2C_DEL 0x18 +/* + * 16-bit field for the number of SCL cycles to wait after rising SCL + * before deciding the slave is not responding. 0 disables the + * timeout detection. + */ #define BCM2835_I2C_CLKT 0x1c #define BCM2835_I2C_C_READ BIT(0) @@ -477,6 +482,12 @@ static int bcm2835_i2c_probe(struct platform_device *pdev) adap->dev.of_node = pdev->dev.of_node; adap->quirks = of_device_get_match_data(&pdev->dev); + /* + * Disable the hardware clock stretching timeout. SMBUS + * specifies a limit for how long the device can stretch the + * clock, but core I2C doesn't. + */ + bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_CLKT, 0); bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, 0); ret = i2c_add_adapter(adap); -- 2.34.1