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 B3901C43460 for ; Wed, 12 May 2021 19:48:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7A9296141C for ; Wed, 12 May 2021 19:48:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1382209AbhELTnY (ORCPT ); Wed, 12 May 2021 15:43:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:51090 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1352403AbhELSDM (ORCPT ); Wed, 12 May 2021 14:03:12 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 867E861434; Wed, 12 May 2021 18:02:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1620842523; bh=OBRM+63/3ohtj24gC1piWGYcbhX4ghxYNsGGNhbXyN4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=blB9Si9i3Z7pis87Sd9QDz3QTviEwrpjH60eIJ9QmtfPXegW6Z7l9eiwhTrz31Oxb NNFDH9Tj0aqfuhNBfC17UAhLd21AYNW/q55czMpq1z3NfmuCohhSppzRFBGG0vvuex GfOkFMbw6fDSJk5vDyON7L47G4NX5AfrsXQ2y3/eWaj6a6nqOtLdDhLlD2sm1OdZi9 C5TuFC+SzKW3apQo5Yp/hYuUiM96be0FXab11oDhTFYLNFf3k7LE2Qle2oLhhsb2tb 2FxdJvlFB+3jImCICONysjkGfjGCHdk/SCgwRs8HnTe0OoAul3tCgNnZjLYTezcCYi DfrpiX6JeJwhg== 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 5.12 37/37] net: stmmac: Do not enable RX FIFO overflow interrupts Date: Wed, 12 May 2021 14:01:04 -0400 Message-Id: <20210512180104.664121-37-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210512180104.664121-1-sashal@kernel.org> References: <20210512180104.664121-1-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 62aa0e95beb7..a7249e4071f1 100644 --- a/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c @@ -222,7 +222,7 @@ 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)); @@ -283,11 +283,6 @@ 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 4749bd0af160..a23797267ad0 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c @@ -4162,7 +4162,6 @@ 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 */ @@ -4173,17 +4172,8 @@ 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