From patchwork Wed Feb 19 10:54:23 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Esben Haabendal X-Patchwork-Id: 11391247 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 8DE0E14E3 for ; Wed, 19 Feb 2020 10:54:46 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 5852C2464E for ; Wed, 19 Feb 2020 10:54:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="nIWoYTM4"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=geanix.com header.i=@geanix.com header.b="ToWkT2Zf" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5852C2464E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=geanix.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=oerrTRjd7RRluAb5kwiIZW1/f1I9yuWRML4UrdbfYIc=; b=nIWoYTM4LOJg4Z M0p4YJKyfv7MZfdQ1o+ODSUbEPrUyoUD7JzZqa4Rt4BAfDG2NzVVQC8UECF7pNF9FvX3jLfLZFkut WQciZWruoslWq9yCRGiU5zzKdfgyWEBG2no/fMCv3Ne5kN2ArE3z7sxo1UoW+u+L+OKoQ0hEXZPoy K8c91ATNi7gRWugwANYFODKB9dq9uC97YZs8sA/MjZGkeGy3LuD2u7y/vLywzf/zimT69S567ZnOs oi5cizEKhp++gyn3nvYjEEKGew+4GP4beSrHyF4w8w6TRNS2xFy6wG057BRW9uWwULBsVsBRObu6y 8hB3WmrA4ttC7YEVf3Jg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1j4N05-0003iZ-Qu; Wed, 19 Feb 2020 10:54:41 +0000 Received: from first.geanix.com ([116.203.34.67]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1j4Mzq-0003Uk-TI for linux-arm-kernel@lists.infradead.org; Wed, 19 Feb 2020 10:54:28 +0000 Received: from localhost (_gateway [172.20.0.1]) by first.geanix.com (Postfix) with ESMTPSA id 39F58C002E; Wed, 19 Feb 2020 10:54:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=geanix.com; s=first; t=1582109664; bh=VYzKQ++/LYo+JsJQba43uJIM0DxFk+Tyra4KIcUC6ok=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ToWkT2ZfnJ5WjreqQSliA3cmR8LK8Opg/rzbo23501MrL/0av9f+fF45I1FkFzNCe Xlcru5V6JEsg6nus6IyJMIqY1yDywGvWl7JuzR04Rf2vABGW3kvmXwSv+7syjwY/VP CoR1g+iUNtgxJnjSwAi3nZJWA9u5LCXey2nTLwwihHWzayBJ7xQzkVdhvsz2YQIlQA hFrLtcoo95giSTQF85ff7XcGZ9ZAQ9zHQrrHTQaSzUN7mPZya80WSiKQC9c2fYKbSU ZraIHf3N1o041Z1L5bgI9YCYl7bbzMqYJbeh4cX1j4qVMfGA2SHKRtfmSK3/mmfgS1 PpJjCpfdJ5/jw== From: Esben Haabendal To: netdev@vger.kernel.org Subject: [PATCH net 4/4] net: ll_temac: Handle DMA halt condition caused by buffer underrun Date: Wed, 19 Feb 2020 11:54:23 +0100 Message-Id: X-Mailer: git-send-email 2.25.0 In-Reply-To: References: MIME-Version: 1.0 X-Spam-Status: No, score=-1.7 required=4.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,UNPARSEABLE_RELAY,URIBL_BLOCKED autolearn=disabled version=3.4.3 X-Spam-Checker-Version: SpamAssassin 3.4.3 (2019-12-06) on eb9da72b0f73 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200219_025427_348984_853593C7 X-CRM114-Status: GOOD ( 16.13 ) X-Spam-Score: -0.2 (/) X-Spam-Report: SpamAssassin version 3.4.3 on bombadil.infradead.org summary: Content analysis details: (-0.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 SPF_PASS SPF: sender matches SPF record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Andrew Lunn , Michal Simek , linux-kernel@vger.kernel.org, =?utf-8?q?Petr_=C5=A0tetiar?= , "David S . Miller" , linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org The SDMA engine used by TEMAC halts operation when it has finished processing of the last buffer descriptor in the buffer ring. Unfortunately, no interrupt event is generated when this happens, so we need to setup another mechanism to make sure DMA operation is restarted when enough buffers have been added to the ring. Fixes: 92744989533c ("net: add Xilinx ll_temac device driver") Signed-off-by: Esben Haabendal --- drivers/net/ethernet/xilinx/ll_temac.h | 3 ++ drivers/net/ethernet/xilinx/ll_temac_main.c | 47 ++++++++++++++++++++- 2 files changed, 48 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/xilinx/ll_temac.h b/drivers/net/ethernet/xilinx/ll_temac.h index 99fe059e5c7f..53fb8141f1a6 100644 --- a/drivers/net/ethernet/xilinx/ll_temac.h +++ b/drivers/net/ethernet/xilinx/ll_temac.h @@ -380,6 +380,9 @@ struct temac_local { /* DMA channel control setup */ u32 tx_chnl_ctrl; u32 rx_chnl_ctrl; + u8 coalesce_count_rx; + + struct delayed_work restart_work; }; /* Wrappers for temac_ior()/temac_iow() function pointers above */ diff --git a/drivers/net/ethernet/xilinx/ll_temac_main.c b/drivers/net/ethernet/xilinx/ll_temac_main.c index 255207f2fd27..90b486becb5b 100644 --- a/drivers/net/ethernet/xilinx/ll_temac_main.c +++ b/drivers/net/ethernet/xilinx/ll_temac_main.c @@ -51,6 +51,7 @@ #include #include #include +#include #include #include #include @@ -920,6 +921,17 @@ temac_start_xmit(struct sk_buff *skb, struct net_device *ndev) return NETDEV_TX_OK; } +static int ll_temac_recv_buffers_available(struct temac_local *lp) +{ + int available; + + if (!lp->rx_skb[lp->rx_bd_ci]) + return 0; + available = 1 + lp->rx_bd_tail - lp->rx_bd_ci; + if (available <= 0) + available += RX_BD_NUM; + return available; +} static void ll_temac_recv(struct net_device *ndev) { @@ -990,6 +1002,18 @@ static void ll_temac_recv(struct net_device *ndev) lp->rx_bd_ci = 0; } while (rx_bd != lp->rx_bd_tail); + /* DMA operations will halt when the last buffer descriptor is + * processed (ie. the one pointed to by RX_TAILDESC_PTR). + * When that happens, no more interrupt events will be + * generated. No IRQ_COAL or IRQ_DLY, and not even an + * IRQ_ERR. To avoid stalling, we schedule a delayed work + * when there is a potential risk of that happening. The work + * will call this function, and thus re-schedule itself until + * enough buffers are available again. + */ + if (ll_temac_recv_buffers_available(lp) < lp->coalesce_count_rx) + schedule_delayed_work(&lp->restart_work, HZ / 1000); + /* Allocate new buffers for those buffer descriptors that were * passed to network stack. Note that GFP_ATOMIC allocations * can fail (e.g. when a larger burst of GFP_ATOMIC @@ -1045,6 +1069,18 @@ static void ll_temac_recv(struct net_device *ndev) spin_unlock_irqrestore(&lp->rx_lock, flags); } +/* Function scheduled to ensure a restart in case of DMA halt + * condition caused by running out of buffer descriptors. + */ +static void ll_temac_restart_work_func(struct work_struct *work) +{ + struct temac_local *lp = container_of(work, struct temac_local, + restart_work.work); + struct net_device *ndev = lp->ndev; + + ll_temac_recv(ndev); +} + static irqreturn_t ll_temac_tx_irq(int irq, void *_ndev) { struct net_device *ndev = _ndev; @@ -1137,6 +1173,8 @@ static int temac_stop(struct net_device *ndev) dev_dbg(&ndev->dev, "temac_close()\n"); + cancel_delayed_work_sync(&lp->restart_work); + free_irq(lp->tx_irq, ndev); free_irq(lp->rx_irq, ndev); @@ -1258,6 +1296,7 @@ static int temac_probe(struct platform_device *pdev) lp->dev = &pdev->dev; lp->options = XTE_OPTION_DEFAULTS; spin_lock_init(&lp->rx_lock); + INIT_DELAYED_WORK(&lp->restart_work, ll_temac_restart_work_func); /* Setup mutex for synchronization of indirect register access */ if (pdata) { @@ -1364,6 +1403,7 @@ static int temac_probe(struct platform_device *pdev) */ lp->tx_chnl_ctrl = 0x10220000; lp->rx_chnl_ctrl = 0xff070000; + lp->coalesce_count_rx = 0x07; /* Finished with the DMA node; drop the reference */ of_node_put(dma_np); @@ -1395,11 +1435,14 @@ static int temac_probe(struct platform_device *pdev) (pdata->tx_irq_count << 16); else lp->tx_chnl_ctrl = 0x10220000; - if (pdata->rx_irq_timeout || pdata->rx_irq_count) + if (pdata->rx_irq_timeout || pdata->rx_irq_count) { lp->rx_chnl_ctrl = (pdata->rx_irq_timeout << 24) | (pdata->rx_irq_count << 16); - else + lp->coalesce_count_rx = pdata->rx_irq_count; + } else { lp->rx_chnl_ctrl = 0xff070000; + lp->coalesce_count_rx = 0x07; + } } /* Error handle returned DMA RX and TX interrupts */