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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 802A7C10F14 for ; Thu, 10 Oct 2019 12:18:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 610EF2054F for ; Thu, 10 Oct 2019 12:18:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387721AbfJJMS3 (ORCPT ); Thu, 10 Oct 2019 08:18:29 -0400 Received: from metis.ext.pengutronix.de ([85.220.165.71]:40471 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733250AbfJJMSN (ORCPT ); Thu, 10 Oct 2019 08:18:13 -0400 Received: from heimdall.vpn.pengutronix.de ([2001:67c:670:205:1d::14] helo=blackshift.org) by metis.ext.pengutronix.de with esmtp (Exim 4.92) (envelope-from ) id 1iIXOM-0006Lw-8P; Thu, 10 Oct 2019 14:18:02 +0200 From: Marc Kleine-Budde To: netdev@vger.kernel.org, linux-can Cc: davem@davemloft.net, kernel@pengutronix.de, jhofstee@victronenergy.com, =?UTF-8?q?Martin=20Hundeb=C3=B8ll?= , Kurt Van Dijck , Wolfgang Grandegger , Joe Burmeister , linux-stable , Marc Kleine-Budde Subject: [PATCH 08/29] can: c_can: c_can_poll(): only read status register after status IRQ Date: Thu, 10 Oct 2019 14:17:29 +0200 Message-Id: <20191010121750.27237-9-mkl@pengutronix.de> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191010121750.27237-1-mkl@pengutronix.de> References: <20191010121750.27237-1-mkl@pengutronix.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 2001:67c:670:205:1d::14 X-SA-Exim-Mail-From: mkl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: stable@vger.kernel.org Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Kurt Van Dijck When the status register is read without the status IRQ pending, the chip may not raise the interrupt line for an upcoming status interrupt and the driver may miss a status interrupt. It is critical that the BUSOFF status interrupt is forwarded to the higher layers, since no more interrupts will follow without intervention. Thanks to Wolfgang and Joe for bringing up the first idea. Signed-off-by: Kurt Van Dijck Cc: Wolfgang Grandegger Cc: Joe Burmeister Fixes: fa39b54ccf28 ("can: c_can: Get rid of pointless interrupts") Cc: linux-stable Signed-off-by: Marc Kleine-Budde --- drivers/net/can/c_can/c_can.c | 25 ++++++++++++++++++++----- drivers/net/can/c_can/c_can.h | 1 + 2 files changed, 21 insertions(+), 5 deletions(-) diff --git a/drivers/net/can/c_can/c_can.c b/drivers/net/can/c_can/c_can.c index 606b7d8ffe13..9b61bfbea6cd 100644 --- a/drivers/net/can/c_can/c_can.c +++ b/drivers/net/can/c_can/c_can.c @@ -97,6 +97,9 @@ #define BTR_TSEG2_SHIFT 12 #define BTR_TSEG2_MASK (0x7 << BTR_TSEG2_SHIFT) +/* interrupt register */ +#define INT_STS_PENDING 0x8000 + /* brp extension register */ #define BRP_EXT_BRPE_MASK 0x0f #define BRP_EXT_BRPE_SHIFT 0 @@ -1029,10 +1032,16 @@ static int c_can_poll(struct napi_struct *napi, int quota) u16 curr, last = priv->last_status; int work_done = 0; - priv->last_status = curr = priv->read_reg(priv, C_CAN_STS_REG); - /* Ack status on C_CAN. D_CAN is self clearing */ - if (priv->type != BOSCH_D_CAN) - priv->write_reg(priv, C_CAN_STS_REG, LEC_UNUSED); + /* Only read the status register if a status interrupt was pending */ + if (atomic_xchg(&priv->sie_pending, 0)) { + priv->last_status = curr = priv->read_reg(priv, C_CAN_STS_REG); + /* Ack status on C_CAN. D_CAN is self clearing */ + if (priv->type != BOSCH_D_CAN) + priv->write_reg(priv, C_CAN_STS_REG, LEC_UNUSED); + } else { + /* no change detected ... */ + curr = last; + } /* handle state changes */ if ((curr & STATUS_EWARN) && (!(last & STATUS_EWARN))) { @@ -1083,10 +1092,16 @@ static irqreturn_t c_can_isr(int irq, void *dev_id) { struct net_device *dev = (struct net_device *)dev_id; struct c_can_priv *priv = netdev_priv(dev); + int reg_int; - if (!priv->read_reg(priv, C_CAN_INT_REG)) + reg_int = priv->read_reg(priv, C_CAN_INT_REG); + if (!reg_int) return IRQ_NONE; + /* save for later use */ + if (reg_int & INT_STS_PENDING) + atomic_set(&priv->sie_pending, 1); + /* disable all interrupts and schedule the NAPI */ c_can_irq_control(priv, false); napi_schedule(&priv->napi); diff --git a/drivers/net/can/c_can/c_can.h b/drivers/net/can/c_can/c_can.h index 8acdc7fa4792..d5567a7c1c6d 100644 --- a/drivers/net/can/c_can/c_can.h +++ b/drivers/net/can/c_can/c_can.h @@ -198,6 +198,7 @@ struct c_can_priv { struct net_device *dev; struct device *device; atomic_t tx_active; + atomic_t sie_pending; unsigned long tx_dir; int last_status; u16 (*read_reg) (const struct c_can_priv *priv, enum reg index); -- 2.23.0