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=-11.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 83AD4CA9ED3 for ; Mon, 4 Nov 2019 16:43:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 50A02214B2 for ; Mon, 4 Nov 2019 16:43:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1572885790; bh=DKp1hX1uGHfWYj8nNqmLmHKnvnd9J7wr+v+K7kpo8fE=; h=Subject:To:From:Date:List-ID:From; b=b2CWn3iPUMRIgNA8dMeychpcrh2icpGzIZsgfBz63SLqriYQhlF0zfgwIrHgiFAnj XGH+GoHbiWRe0Y1LGJz3wJ0NMva///tBWcH3bMw2DupLYaxqcRyyj3ck2IvL/K+n+b gAc3xrzGaCIE3qtC+n1cmd0A+ELFS8UhpH1QQCcQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729248AbfKDQnJ (ORCPT ); Mon, 4 Nov 2019 11:43:09 -0500 Received: from mail.kernel.org ([198.145.29.99]:36086 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727861AbfKDQnJ (ORCPT ); Mon, 4 Nov 2019 11:43:09 -0500 Received: from localhost (host6-102.lan-isdn.imaginet.fr [195.68.6.102]) (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 7108B20869; Mon, 4 Nov 2019 16:43:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1572885788; bh=DKp1hX1uGHfWYj8nNqmLmHKnvnd9J7wr+v+K7kpo8fE=; h=Subject:To:From:Date:From; b=APLEaj9mRj+3rsvwNPNrG+Fzv289iEk0H5RT1O/iyteg/89krI3mYLUBoCJRK0boz SfmZ3DO5PFDXyPCw6fe/F2BLTczzCXlEUL/Lu4VMbXpT8xusfDtK6xWxnatV88ekk9 yQToiwtAJbYxYdnFi7cpUt6+olhMHSny9kkgPFKg= Subject: patch "tty: serial: msm_serial: Fix flow control" added to tty-testing To: jeffrey.l.hugo@gmail.com, agross@kernel.org, bjorn.andersson@linaro.org, gregkh@linuxfoundation.org, stable@vger.kernel.org From: Date: Mon, 04 Nov 2019 17:42:58 +0100 Message-ID: <157288577886132@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org 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 tty: serial: msm_serial: Fix flow control 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-testing 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 be merged to the tty-next branch sometime soon, after it passes testing, and the merge window is open. If you have any questions about this process, please let me know. >From b027ce258369cbfa88401a691c23dad01deb9f9b Mon Sep 17 00:00:00 2001 From: Jeffrey Hugo Date: Mon, 21 Oct 2019 08:46:16 -0700 Subject: tty: serial: msm_serial: Fix flow control hci_qca interfaces to the wcn3990 via a uart_dm on the msm8998 mtp and Lenovo Miix 630 laptop. As part of initializing the wcn3990, hci_qca disables flow, configures the uart baudrate, and then reenables flow - at which point an event is expected to be received over the uart from the wcn3990. It is observed that this event comes after the baudrate change but before hci_qca re-enables flow. This is unexpected, and is a result of msm_reset() being broken. According to the uart_dm hardware documentation, it is recommended that automatic hardware flow control be enabled by setting RX_RDY_CTL. Auto hw flow control will manage RFR based on the configured watermark. When there is space to receive data, the hw will assert RFR. When the watermark is hit, the hw will de-assert RFR. The hardware documentation indicates that RFR can me manually managed via CR when RX_RDY_CTL is not set. SET_RFR asserts RFR, and RESET_RFR de-asserts RFR. msm_reset() is broken because after resetting the hardware, it unconditionally asserts RFR via SET_RFR. This enables flow regardless of the current configuration, and would undo a previous flow disable operation. It should instead de-assert RFR via RESET_RFR to block flow until the hardware is reconfigured. msm_serial should rely on the client to specify that flow should be enabled, either via mctrl() or the termios structure, and only assert RFR in response to those triggers. Fixes: 04896a77a97b ("msm_serial: serial driver for MSM7K onboard serial peripheral.") Signed-off-by: Jeffrey Hugo Reviewed-by: Bjorn Andersson Cc: stable Reviewed-by: Andy Gross Link: https://lore.kernel.org/r/20191021154616.25457-1-jeffrey.l.hugo@gmail.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/msm_serial.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c index 3657a24913fc..00964b6e4ac1 100644 --- a/drivers/tty/serial/msm_serial.c +++ b/drivers/tty/serial/msm_serial.c @@ -980,6 +980,7 @@ static unsigned int msm_get_mctrl(struct uart_port *port) static void msm_reset(struct uart_port *port) { struct msm_port *msm_port = UART_TO_MSM(port); + unsigned int mr; /* reset everything */ msm_write(port, UART_CR_CMD_RESET_RX, UART_CR); @@ -987,7 +988,10 @@ static void msm_reset(struct uart_port *port) msm_write(port, UART_CR_CMD_RESET_ERR, UART_CR); msm_write(port, UART_CR_CMD_RESET_BREAK_INT, UART_CR); msm_write(port, UART_CR_CMD_RESET_CTS, UART_CR); - msm_write(port, UART_CR_CMD_SET_RFR, UART_CR); + msm_write(port, UART_CR_CMD_RESET_RFR, UART_CR); + mr = msm_read(port, UART_MR1); + mr &= ~UART_MR1_RX_RDY_CTL; + msm_write(port, mr, UART_MR1); /* Disable DM modes */ if (msm_port->is_uartdm) -- 2.23.0