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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 4555CC43331 for ; Mon, 11 Nov 2019 18:30:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1F6B721872 for ; Mon, 11 Nov 2019 18:30:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573497024; bh=MegO0AW1S5ijek+lrnxfYqx5M+fzH8XtDZcN2iYagM4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=kRoluBux6WpobCx5qcSS47+2nFJr3aFMyqFSfKSIZ8S+yNthrja2kAEKUAVGI3VBI ECYsMNkob4Fm2PNhhdI5pmYGip4Z6nSODNoK6/OCg5Jm9I4d7odV2XsA+cr5fUlt5B krJKX17ymH6yCcUNi68XcGGkLxxvj2RafGe9YQtU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726834AbfKKSaW (ORCPT ); Mon, 11 Nov 2019 13:30:22 -0500 Received: from mail.kernel.org ([198.145.29.99]:46640 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726949AbfKKSaW (ORCPT ); Mon, 11 Nov 2019 13:30:22 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5030B21872; Mon, 11 Nov 2019 18:30:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573497020; bh=MegO0AW1S5ijek+lrnxfYqx5M+fzH8XtDZcN2iYagM4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LowKHiSZD8KmweMKpsKjnMyLcUozEZLtZaRLktWqoHrHDVMYCUKBiNyMi70lN58Du 2siHjSB68Ofr+dcWZz8yEhl/e11UV5wkyJFN3y9yroKVr78aNMpjNpklF28+GfTHLN 36WK6JN6u9MViheNZK/1U7AS9XXtCZcqOe7gDOPs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Kurt Van Dijck , Wolfgang Grandegger , Joe Burmeister , Marc Kleine-Budde Subject: [PATCH 4.4 19/43] can: c_can: c_can_poll(): only read status register after status IRQ Date: Mon, 11 Nov 2019 19:28:33 +0100 Message-Id: <20191111181309.592648424@linuxfoundation.org> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191111181246.772983347@linuxfoundation.org> References: <20191111181246.772983347@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Kurt Van Dijck commit 3cb3eaac52c0f145d895f4b6c22834d5f02b8569 upstream. 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 Signed-off-by: Greg Kroah-Hartman --- 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(-) --- 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 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, vo { 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); --- 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);