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 X-Spam-Level: X-Spam-Status: No, score=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 738F9C07E99 for ; Mon, 12 Jul 2021 08:09:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 53CD161151 for ; Mon, 12 Jul 2021 08:09:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350124AbhGLIM1 (ORCPT ); Mon, 12 Jul 2021 04:12:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:55946 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1354001AbhGLIDX (ORCPT ); Mon, 12 Jul 2021 04:03:23 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 7D52461A19; Mon, 12 Jul 2021 07:59:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626076755; bh=2DjKnuJYo6CRy0mLMm13Hc7BpLJ2aMnbSkwUhZ5AR50=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=yErIcvLl9mYKHLb/2xdJTq76avZBgwNp/HcVP1T0wa6cERUXQvL4RDTIZJTcAbCc/ v+EUWjxka8FokCPNLKul1W1HeQgDhTAy2TD3PD8LGxezVxx28pzxJlUzOVhAxd9+RE 15L9ZK0aGjNPRfn/7PJR4FqbhfcELt+XHuPfCTzw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Chris Packham , Wolfram Sang , Sasha Levin Subject: [PATCH 5.13 779/800] i2c: mpc: Restore reread of I2C status register Date: Mon, 12 Jul 2021 08:13:22 +0200 Message-Id: <20210712061049.723306779@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210712060912.995381202@linuxfoundation.org> References: <20210712060912.995381202@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: Chris Packham [ Upstream commit 763778cd79267dadf0ec7e044caf7563df0ab597 ] Prior to commit 1538d82f4647 ("i2c: mpc: Interrupt driven transfer") the old interrupt handler would reread MPC_I2C_SR after checking the CSR_MIF bit. When the driver was re-written this was removed as it seemed unnecessary. However as it turns out this is necessary for i2c devices which do clock stretching otherwise we end up thinking the bus is still busy when processing the interrupt. Fixes: 1538d82f4647 ("i2c: mpc: Interrupt driven transfer") Signed-off-by: Chris Packham Signed-off-by: Wolfram Sang Signed-off-by: Sasha Levin --- drivers/i2c/busses/i2c-mpc.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c index dcca9c2396db..6d5014ebaab5 100644 --- a/drivers/i2c/busses/i2c-mpc.c +++ b/drivers/i2c/busses/i2c-mpc.c @@ -635,6 +635,8 @@ static irqreturn_t mpc_i2c_isr(int irq, void *dev_id) status = readb(i2c->base + MPC_I2C_SR); if (status & CSR_MIF) { + /* Read again to allow register to stabilise */ + status = readb(i2c->base + MPC_I2C_SR); writeb(0, i2c->base + MPC_I2C_SR); mpc_i2c_do_intr(i2c, status); return IRQ_HANDLED; -- 2.30.2