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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 46CAFC4332F for ; Wed, 9 Nov 2022 12:05:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229554AbiKIMFQ (ORCPT ); Wed, 9 Nov 2022 07:05:16 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43470 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229447AbiKIMFP (ORCPT ); Wed, 9 Nov 2022 07:05:15 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3F12D2AC72 for ; Wed, 9 Nov 2022 04:05:15 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 005B0B81E00 for ; Wed, 9 Nov 2022 12:05:13 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 54F8BC433C1; Wed, 9 Nov 2022 12:05:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1667995512; bh=J3hyjMGYx4Ff8ChBf313j5Q1MIkz+M2384BDHvU/rJI=; h=Subject:To:From:Date:From; b=03uOszCWRIYd8/7GB5WDZNXPrSDQ6ndNfe6HFMtJl/terg+RmZQd35MoLc7zWueVq PVVp8H3t4ZAuwBfLDSxLwHod3j29BxEmdPcTaZwmdxEpt5obROiK3jsSKQM2w3wrdJ q2oGAA0CIFILOVZ0nh5/2Jq2MAaPTcyyrfogVg90= Subject: patch "serial: 8250: Fall back to non-DMA Rx if IIR_RDI occurs" added to tty-linus To: ilpo.jarvinen@linux.intel.com, aman.kumar@intel.com, andriy.shevchenko@linux.intel.com, gregkh@linuxfoundation.org, srikanth.thokala@intel.com, stable@vger.kernel.org From: Date: Wed, 09 Nov 2022 13:05:10 +0100 Message-ID: <166799551093207@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org This is a note to let you know that I've just added the patch titled serial: 8250: Fall back to non-DMA Rx if IIR_RDI occurs to my tty git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git in the tty-linus branch. The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.) The patch will hopefully also be merged in Linus's tree for the next -rc kernel release. If you have any questions about this process, please let me know. >From a931237cbea256aff13bb403da13a97b2d1605d9 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Date: Tue, 8 Nov 2022 14:19:49 +0200 Subject: serial: 8250: Fall back to non-DMA Rx if IIR_RDI occurs MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit DW UART sometimes triggers IIR_RDI during DMA Rx when IIR_RX_TIMEOUT should have been triggered instead. Since IIR_RDI has higher priority than IIR_RX_TIMEOUT, this causes the Rx to hang into interrupt loop. The problem seems to occur at least with some combinations of small-sized transfers (I've reproduced the problem on Elkhart Lake PSE UARTs). If there's already an on-going Rx DMA and IIR_RDI triggers, fall graciously back to non-DMA Rx. That is, behave as if IIR_RX_TIMEOUT had occurred. 8250_omap already considers IIR_RDI similar to this change so its nothing unheard of. Fixes: 75df022b5f89 ("serial: 8250_dma: Fix RX handling") Cc: Co-developed-by: Srikanth Thokala Signed-off-by: Srikanth Thokala Co-developed-by: Aman Kumar Signed-off-by: Aman Kumar Signed-off-by: Ilpo Järvinen Reviewed-by: Andy Shevchenko Link: https://lore.kernel.org/r/20221108121952.5497-2-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/8250/8250_port.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index fe8662cd9402..92dd18716169 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -1897,6 +1897,10 @@ EXPORT_SYMBOL_GPL(serial8250_modem_status); static bool handle_rx_dma(struct uart_8250_port *up, unsigned int iir) { switch (iir & 0x3f) { + case UART_IIR_RDI: + if (!up->dma->rx_running) + break; + fallthrough; case UART_IIR_RX_TIMEOUT: serial8250_rx_dma_flush(up); fallthrough; -- 2.38.1