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=-19.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 11349C4646B for ; Wed, 12 May 2021 19:57:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D40DC61412 for ; Wed, 12 May 2021 19:57:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1384163AbhELT5L (ORCPT ); Wed, 12 May 2021 15:57:11 -0400 Received: from mail.kernel.org ([198.145.29.99]:54566 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1349609AbhELSKL (ORCPT ); Wed, 12 May 2021 14:10:11 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 29E6161938; Wed, 12 May 2021 18:05:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1620842721; bh=LmqfkwMYhKqF6Tm30FO7R7fI8lbJNQQOUGeggJ/jTfA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nGy4jfjl1iHmW4sJYZFsX5j+ZhB3JN+3c7KeAFNhe1cHTljhcL7sZNMHsTbB5+RIr 0FcWWrJkM8DNtffysCIFetT3CXLwZica1BwfA6XmTDbgc8CRuD0Dk4PDfN0CkRB3OA K5+rjt3VUy7zgUcbFeNuzkbzN9+nyP0/lmRa6LcWXRraaE1njRAu7mj8mv2aKFZXq+ gp6j8Uvb991pDihJWCpwUWyfoStpGgRjLG7/uzYAv9x8hzFs2WEaN2QDZ2D0RquJQk 8Xeb/IPyWe2M4TRbXsjvxNwyOi1p/DjyWJ5OVNsiOWIWemHbYRqK+deHrnrFI5Abdy FNaxUl4R9guNA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Yannick Vignon , Jakub Kicinski , Sasha Levin , netdev@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org Subject: [PATCH AUTOSEL 4.19 18/18] net: stmmac: Do not enable RX FIFO overflow interrupts Date: Wed, 12 May 2021 14:04:49 -0400 Message-Id: <20210512180450.665586-18-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210512180450.665586-1-sashal@kernel.org> References: <20210512180450.665586-1-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: Yannick Vignon [ Upstream commit 8a7cb245cf28cb3e541e0d6c8624b95d079e155b ] The RX FIFO overflows when the system is not able to process all received packets and they start accumulating (first in the DMA queue in memory, then in the FIFO). An interrupt is then raised for each overflowing packet and handled in stmmac_interrupt(). This is counter-productive, since it brings the system (or more likely, one CPU core) to its knees to process the FIFO overflow interrupts. stmmac_interrupt() handles overflow interrupts by writing the rx tail ptr into the corresponding hardware register (according to the MAC spec, this has the effect of restarting the MAC DMA). However, without freeing any rx descriptors, the DMA stops right away, and another overflow interrupt is raised as the FIFO overflows again. Since the DMA is already restarted at the end of stmmac_rx_refill() after freeing descriptors, disabling FIFO overflow interrupts and the corresponding handling code has no side effect, and eliminates the interrupt storm when the RX FIFO overflows. Signed-off-by: Yannick Vignon Link: https://lore.kernel.org/r/20210506143312.20784-1-yannick.vignon@oss.nxp.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c | 7 +------ drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 14 ++------------ 2 files changed, 3 insertions(+), 18 deletions(-) diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c b/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c index 8c3780d1105f..232efe17ac2c 100644 --- a/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c @@ -214,7 +214,7 @@ static void dwmac4_dma_rx_chan_op_mode(void __iomem *ioaddr, int mode, u32 channel, int fifosz, u8 qmode) { unsigned int rqs = fifosz / 256 - 1; - u32 mtl_rx_op, mtl_rx_int; + u32 mtl_rx_op; mtl_rx_op = readl(ioaddr + MTL_CHAN_RX_OP_MODE(channel)); @@ -285,11 +285,6 @@ static void dwmac4_dma_rx_chan_op_mode(void __iomem *ioaddr, int mode, } writel(mtl_rx_op, ioaddr + MTL_CHAN_RX_OP_MODE(channel)); - - /* Enable MTL RX overflow */ - mtl_rx_int = readl(ioaddr + MTL_CHAN_INT_CTRL(channel)); - writel(mtl_rx_int | MTL_RX_OVERFLOW_INT_EN, - ioaddr + MTL_CHAN_INT_CTRL(channel)); } static void dwmac4_dma_tx_chan_op_mode(void __iomem *ioaddr, int mode, diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c index a1443d7197e8..af59761ddfa0 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c @@ -3706,7 +3706,6 @@ static irqreturn_t stmmac_interrupt(int irq, void *dev_id) /* To handle GMAC own interrupts */ if ((priv->plat->has_gmac) || xmac) { int status = stmmac_host_irq_status(priv, priv->hw, &priv->xstats); - int mtl_status; if (unlikely(status)) { /* For LPI we need to save the tx status */ @@ -3717,17 +3716,8 @@ static irqreturn_t stmmac_interrupt(int irq, void *dev_id) } for (queue = 0; queue < queues_count; queue++) { - struct stmmac_rx_queue *rx_q = &priv->rx_queue[queue]; - - mtl_status = stmmac_host_mtl_irq_status(priv, priv->hw, - queue); - if (mtl_status != -EINVAL) - status |= mtl_status; - - if (status & CORE_IRQ_MTL_RX_OVERFLOW) - stmmac_set_rx_tail_ptr(priv, priv->ioaddr, - rx_q->rx_tail_addr, - queue); + status = stmmac_host_mtl_irq_status(priv, priv->hw, + queue); } /* PCS link status */ -- 2.30.2