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 F1E06C433F5 for ; Wed, 23 Feb 2022 02:28:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236856AbiBWC3K (ORCPT ); Tue, 22 Feb 2022 21:29:10 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42150 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236789AbiBWC3A (ORCPT ); Tue, 22 Feb 2022 21:29:00 -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 840523DDD0; Tue, 22 Feb 2022 18:28:33 -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 41025B81E09; Wed, 23 Feb 2022 02:28:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 68053C340E8; Wed, 23 Feb 2022 02:28:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1645583310; bh=YfYYgfEG/tUw+RF/Z5+2ChlPUubhZWSVdHx6WExWyhs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sxZTsLrO/QH9RMk9HY9+yVIW6Vf7+rlHhGWNeaRKZgCmvAMWssxne1X6hvKpJDcep nBxT9Qzl4+0WLJIwIAFGLmf6hjfJOaw1N22XHMAtssdzdpyQfabelqmkqweLFKHz5e eXBZ7VLdSfL3BYHGhe2FuIkS+yy2bk8MDXtDslt8TEXbPqgrihlDpm0pYNjsNdFfst SVdSenh9LC1sikhCzXAjtHncks+XIn9fnG/fuIY01V4b5kAzT7Og7zOR8libkUCSgB WCOnkrcD6xeUeE90raQ2B9i6CAgjgSlI4sFdMSXiav7a49X77GnQmFClV1KN54V/gy IfJtXX+RkNd/A== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Eric Anholt , Stefan Wahren , Wolfram Sang , Sasha Levin , f.fainelli@gmail.com, rjui@broadcom.com, sbranden@broadcom.com, bcm-kernel-feedback-list@broadcom.com, nsaenz@kernel.org, prabhakar.mahadev-lad.rj@bp.renesas.com, linux-i2c@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH AUTOSEL 5.16 04/30] i2c: bcm2835: Avoid clock stretching timeouts Date: Tue, 22 Feb 2022 21:27:53 -0500 Message-Id: <20220223022820.240649-4-sashal@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220223022820.240649-1-sashal@kernel.org> References: <20220223022820.240649-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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