From patchwork Thu Nov 12 14:42:52 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wolfram Sang X-Patchwork-Id: 7603031 X-Patchwork-Delegate: horms@verge.net.au Return-Path: X-Original-To: patchwork-linux-sh@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id C65AEBF90C for ; Thu, 12 Nov 2015 14:43:17 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id C5B81207B5 for ; Thu, 12 Nov 2015 14:43:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D6A41207AA for ; Thu, 12 Nov 2015 14:43:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752606AbbKLOnO (ORCPT ); Thu, 12 Nov 2015 09:43:14 -0500 Received: from sauhun.de ([89.238.76.85]:55603 "EHLO pokefinder.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752394AbbKLOnO (ORCPT ); Thu, 12 Nov 2015 09:43:14 -0500 Received: from p4fe252ca.dip0.t-ipconnect.de ([79.226.82.202]:55376 helo=localhost) by pokefinder.org with esmtpsa (TLS1.2:RSA_AES_128_CBC_SHA1:128) (Exim 4.80) (envelope-from ) id 1Zwt5k-0008W4-96; Thu, 12 Nov 2015 15:43:12 +0100 From: Wolfram Sang To: linux-i2c@vger.kernel.org Cc: linux-sh@vger.kernel.org, Magnus Damm , Simon Horman , Laurent Pinchart , Geert Uytterhoeven , Wolfram Sang , Yoshihiro Shimoda , Kuninori Morimoto Subject: [PATCH v2 09/10] i2c: rcar: revoke START request early Date: Thu, 12 Nov 2015 15:42:52 +0100 Message-Id: <1447339372-10060-3-git-send-email-wsa@the-dreams.de> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1447339372-10060-1-git-send-email-wsa@the-dreams.de> References: <1447339372-10060-1-git-send-email-wsa@the-dreams.de> Sender: linux-sh-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org X-Spam-Status: No, score=-7.3 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Wolfram Sang If we don't clear START generation as soon as possible, it may cause another message to be generated, e.g. when receiving NACK in address phase. To keep the race window as small as possible, we clear it right at the beginning of the interrupt. We don't need any checks since we always want to stop START and STOP generation on the next occasion after we started it. This patch improves the situation but sadly does not completely fix it. It is still to be researched if we can do better given this HW design. Signed-off-by: Wolfram Sang --- drivers/i2c/busses/i2c-rcar.c | 23 +++++++---------------- 1 file changed, 7 insertions(+), 16 deletions(-) diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c index 8ad4c7d1ad8654..64a01c0177463a 100644 --- a/drivers/i2c/busses/i2c-rcar.c +++ b/drivers/i2c/busses/i2c-rcar.c @@ -83,6 +83,7 @@ #define RCAR_BUS_PHASE_START (MDBS | MIE | ESG) #define RCAR_BUS_PHASE_DATA (MDBS | MIE) +#define RCAR_BUS_MASK_DATA (~(ESG | FSB) & 0xFF) #define RCAR_BUS_PHASE_STOP (MDBS | MIE | FSB) #define RCAR_IRQ_SEND (MNR | MAL | MST | MAT | MDE) @@ -289,13 +290,6 @@ static int rcar_i2c_irq_send(struct rcar_i2c_priv *priv, u32 msr) if (!(msr & MDE)) return 0; - /* - * If address transfer phase finished, - * goto data phase. - */ - if (msr & MAT) - rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_DATA); - if (priv->pos < msg->len) { /* * Prepare next data to ICRXTX register. @@ -347,11 +341,7 @@ static int rcar_i2c_irq_recv(struct rcar_i2c_priv *priv, u32 msr) return 0; if (msr & MAT) { - /* - * Address transfer phase finished, - * but, there is no data at this point. - * Do nothing. - */ + /* Address transfer phase finished, but no data at this point. */ } else if (priv->pos < msg->len) { /* * get received data @@ -367,8 +357,6 @@ static int rcar_i2c_irq_recv(struct rcar_i2c_priv *priv, u32 msr) */ if (priv->pos + 1 >= msg->len) rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_STOP); - else - rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_DATA); if (priv->pos == msg->len && !(priv->flags & ID_LAST_MSG)) rcar_i2c_next_msg(priv); @@ -436,7 +424,11 @@ static bool rcar_i2c_slave_irq(struct rcar_i2c_priv *priv) static irqreturn_t rcar_i2c_irq(int irq, void *ptr) { struct rcar_i2c_priv *priv = ptr; - u32 msr; + u32 msr, val; + + /* Clear START or STOP as soon as we can */ + val = rcar_i2c_read(priv, ICMCR); + rcar_i2c_write(priv, ICMCR, val & RCAR_BUS_MASK_DATA); msr = rcar_i2c_read(priv, ICMSR); @@ -458,7 +450,6 @@ static irqreturn_t rcar_i2c_irq(int irq, void *ptr) /* Nack */ if (msr & MNR) { /* HW automatically sends STOP after received NACK */ - rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_DATA); rcar_i2c_write(priv, ICMIER, RCAR_IRQ_STOP); rcar_i2c_flags_set(priv, ID_NACK); goto out;