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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,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 2DA05C11F80 for ; Mon, 12 Jul 2021 09:03:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 16F546101E for ; Mon, 12 Jul 2021 09:03:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353133AbhGLJE2 (ORCPT ); Mon, 12 Jul 2021 05:04:28 -0400 Received: from mail.kernel.org ([198.145.29.99]:55676 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1354058AbhGLID1 (ORCPT ); Mon, 12 Jul 2021 04:03:27 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id E6C5861209; Mon, 12 Jul 2021 07:59:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626076787; bh=SzXXGwELldSFDVJ8fOhuI8+fI6lsfYhNSsFaUkVuMy0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=1PUZqPlwiDiRpPU4SUiqWzXvgHAoLluI21owqG0ABl6ctzo7gIdKledj0tOJ5brtU I0t5FjrQxMuQt2ZLEwdIHZLYB476pzM6A/J/CRAAPnQUfnfdnr5+gNXH+Zh3UmFiwA KD6vRxp0QoR0KK+RTSLFaTU9pK+NIrf/dPzMnBb8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jan Kiszka , Vignesh Raghavendra , Sasha Levin Subject: [PATCH 5.13 751/800] serial: 8250: 8250_omap: Fix possible interrupt storm on K3 SoCs Date: Mon, 12 Jul 2021 08:12:54 +0200 Message-Id: <20210712061046.701821354@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210712060912.995381202@linuxfoundation.org> References: <20210712060912.995381202@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Vignesh Raghavendra [ Upstream commit b67e830d38fa9335d927fe67e812e3ed81b4689c ] On K3 family of SoCs (which includes AM654 SoC), it is observed that RX TIMEOUT is signalled after RX FIFO has been drained, in which case a dummy read of RX FIFO is required to clear RX TIMEOUT condition. Otherwise, this would lead to an interrupt storm. Fix this by introducing UART_RX_TIMEOUT_QUIRK flag and doing a dummy read in IRQ handler when RX TIMEOUT is reported with no data in RX FIFO. Fixes: be70874498f3 ("serial: 8250_omap: Add support for AM654 UART controller") Reported-by: Jan Kiszka Tested-by: Jan Kiszka Signed-off-by: Vignesh Raghavendra Link: https://lore.kernel.org/r/20210622145704.11168-1-vigneshr@ti.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/serial/8250/8250_omap.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c index c06631ced414..79418d4beb48 100644 --- a/drivers/tty/serial/8250/8250_omap.c +++ b/drivers/tty/serial/8250/8250_omap.c @@ -43,6 +43,7 @@ #define UART_ERRATA_CLOCK_DISABLE (1 << 3) #define UART_HAS_EFR2 BIT(4) #define UART_HAS_RHR_IT_DIS BIT(5) +#define UART_RX_TIMEOUT_QUIRK BIT(6) #define OMAP_UART_FCR_RX_TRIG 6 #define OMAP_UART_FCR_TX_TRIG 4 @@ -104,6 +105,9 @@ #define UART_OMAP_EFR2 0x23 #define UART_OMAP_EFR2_TIMEOUT_BEHAVE BIT(6) +/* RX FIFO occupancy indicator */ +#define UART_OMAP_RX_LVL 0x64 + struct omap8250_priv { int line; u8 habit; @@ -611,6 +615,7 @@ static int omap_8250_dma_handle_irq(struct uart_port *port); static irqreturn_t omap8250_irq(int irq, void *dev_id) { struct uart_port *port = dev_id; + struct omap8250_priv *priv = port->private_data; struct uart_8250_port *up = up_to_u8250p(port); unsigned int iir; int ret; @@ -625,6 +630,18 @@ static irqreturn_t omap8250_irq(int irq, void *dev_id) serial8250_rpm_get(up); iir = serial_port_in(port, UART_IIR); ret = serial8250_handle_irq(port, iir); + + /* + * On K3 SoCs, it is observed that RX TIMEOUT is signalled after + * FIFO has been drained, in which case a dummy read of RX FIFO + * is required to clear RX TIMEOUT condition. + */ + if (priv->habit & UART_RX_TIMEOUT_QUIRK && + (iir & UART_IIR_RX_TIMEOUT) == UART_IIR_RX_TIMEOUT && + serial_port_in(port, UART_OMAP_RX_LVL) == 0) { + serial_port_in(port, UART_RX); + } + serial8250_rpm_put(up); return IRQ_RETVAL(ret); @@ -1218,7 +1235,8 @@ static struct omap8250_dma_params am33xx_dma = { static struct omap8250_platdata am654_platdata = { .dma_params = &am654_dma, - .habit = UART_HAS_EFR2 | UART_HAS_RHR_IT_DIS, + .habit = UART_HAS_EFR2 | UART_HAS_RHR_IT_DIS | + UART_RX_TIMEOUT_QUIRK, }; static struct omap8250_platdata am33xx_platdata = { -- 2.30.2