From patchwork Mon Nov 9 12:56:11 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 322672 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=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY,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 80239C388F7 for ; Mon, 9 Nov 2020 13:27:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 333E42076E for ; Mon, 9 Nov 2020 13:27:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604928466; bh=TCj67ClWiMRJkTMqqqomrJynDRG5J06ZNnfcLOzKfA0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ZW2JJmQAEw9MqAi+6A//69LoecdSVZszQFQ9QyIer5MVlBM99jB12XNPqnMcF+YXm PHugOEm5Qn1hR7biVmjMY3UybMeCLg6sdSYCeOAV5Qhqc9tJiS1cxetCMRR/K6M24u kL9Rliseb5iJ4xL6b2/s4jJ1lPpT4ysd+cT/od3E= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733215AbgKINOu (ORCPT ); Mon, 9 Nov 2020 08:14:50 -0500 Received: from mail.kernel.org ([198.145.29.99]:41266 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731892AbgKINOt (ORCPT ); Mon, 9 Nov 2020 08:14:49 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E66BC20867; Mon, 9 Nov 2020 13:14:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604927688; bh=TCj67ClWiMRJkTMqqqomrJynDRG5J06ZNnfcLOzKfA0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qq1gf3T7kE595nEOvWjcJLAXY6ZLFbCHRo8vnNzjEp4M+FUG0xgH5CPxfLKltw/+O LJaGxi5Ege+yqyioyJvY85FixvBVucCtKWZA9tUluCU7reeNh73jJT5ZiLzihVXCQM CPZekf3u4pUkg01MAiEjF0UIAnvRSZLv1BoR/oCU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Michael Walle , Vladimir Oltean Subject: [PATCH 5.4 74/85] tty: serial: fsl_lpuart: LS1021A has a FIFO size of 16 words, like LS1028A Date: Mon, 9 Nov 2020 13:56:11 +0100 Message-Id: <20201109125026.130739118@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201109125022.614792961@linuxfoundation.org> References: <20201109125022.614792961@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Vladimir Oltean commit c97f2a6fb3dfbfbbc88edc8ea62ef2b944e18849 upstream. Prior to the commit that this one fixes, the FIFO size was derived from the read-only register LPUARTx_FIFO[TXFIFOSIZE] using the following formula: TX FIFO size = 2 ^ (LPUARTx_FIFO[TXFIFOSIZE] - 1) The documentation for LS1021A is a mess. Under chapter 26.1.3 LS1021A LPUART module special consideration, it mentions TXFIFO_SZ and RXFIFO_SZ being equal to 4, and in the register description for LPUARTx_FIFO, it shows the out-of-reset value of TXFIFOSIZE and RXFIFOSIZE fields as "011", even though these registers read as "101" in reality. And when LPUART on LS1021A was working, the "101" value did correspond to "16 datawords", by applying the formula above, even though the documentation is wrong again (!!!!) and says that "101" means 64 datawords (hint: it doesn't). So the "new" formula created by commit f77ebb241ce0 has all the premises of being wrong for LS1021A, because it relied only on false data and no actual experimentation. Interestingly, in commit c2f448cff22a ("tty: serial: fsl_lpuart: add LS1028A support"), Michael Walle applied a workaround to this by manually setting the FIFO widths for LS1028A. It looks like the same values are used by LS1021A as well, in fact. When the driver thinks that it has a deeper FIFO than it really has, getty (user space) output gets truncated. Many thanks to Michael for pointing out where to look. Fixes: f77ebb241ce0 ("tty: serial: fsl_lpuart: correct the FIFO depth size") Suggested-by: Michael Walle Signed-off-by: Vladimir Oltean Link: https://lore.kernel.org/r/20201023013429.3551026-1-vladimir.oltean@nxp.com Reviewed-by：Fugang Duan Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/fsl_lpuart.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -318,9 +318,10 @@ MODULE_DEVICE_TABLE(of, lpuart_dt_ids); /* Forward declare this for the dma callbacks*/ static void lpuart_dma_tx_complete(void *arg); -static inline bool is_ls1028a_lpuart(struct lpuart_port *sport) +static inline bool is_layerscape_lpuart(struct lpuart_port *sport) { - return sport->devtype == LS1028A_LPUART; + return (sport->devtype == LS1021A_LPUART || + sport->devtype == LS1028A_LPUART); } static inline bool is_imx8qxp_lpuart(struct lpuart_port *sport) @@ -1566,11 +1567,11 @@ static int lpuart32_startup(struct uart_ UARTFIFO_FIFOSIZE_MASK); /* - * The LS1028A has a fixed length of 16 words. Although it supports the - * RX/TXSIZE fields their encoding is different. Eg the reference manual - * states 0b101 is 16 words. + * The LS1021A and LS1028A have a fixed FIFO depth of 16 words. + * Although they support the RX/TXSIZE fields, their encoding is + * different. Eg the reference manual states 0b101 is 16 words. */ - if (is_ls1028a_lpuart(sport)) { + if (is_layerscape_lpuart(sport)) { sport->rxfifo_size = 16; sport->txfifo_size = 16; sport->port.fifosize = sport->txfifo_size;