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=-16.1 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 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 4F4EFC433DB for ; Thu, 4 Feb 2021 15:53:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 19E6064F4D for ; Thu, 4 Feb 2021 15:53:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237636AbhBDPxO (ORCPT ); Thu, 4 Feb 2021 10:53:14 -0500 Received: from mail.kernel.org ([198.145.29.99]:35536 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237570AbhBDPwS (ORCPT ); Thu, 4 Feb 2021 10:52:18 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id D3F2861477; Thu, 4 Feb 2021 15:51:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1612453896; bh=we99LVZdfR8qDwTYTsqf8j51n6oP8RsuHS+ZJSKf63w=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=o5Q+6kxBcvT735pgbAc41XW6uG71OnYJ2PJG4CC5rM6Cxp3sryf7lKf59tfMbVqrY fFhNjcYqSYSvG8TP2Gh477gUCXDrj7baGWg/26eCubRFm8kpo284cmDmSEGyMpTaIR vAf8UgCnxbPGqAapAXgAtBw4L1KBpAYAKR1BWOJQ= Date: Thu, 4 Feb 2021 16:51:33 +0100 From: Greg KH To: zhangqiumiao1@huawei.com Cc: jirislaby@kernel.org, linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org Subject: Re: [PATCH v4] tty: make pl011 serial port driver support 485 mode Message-ID: References: <1612164643-1480-1-git-send-email-zhangqiumiao1@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1612164643-1480-1-git-send-email-zhangqiumiao1@huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 01, 2021 at 03:30:43PM +0800, zhangqiumiao1@huawei.com wrote: > From: Qiumiao Zhang > > make pl011 serial port support 485 mode full duplex communication > > Signed-off-by: Qiumiao Zhang > --- > Changes in v4: > -Add a bound to the loop in pl011_stop_tx > -Remove extra curly braces in pl011_stop_tx > > Changes in v3: > -Fix busy loop forever in pl011_tx_empty > -Move the definition of cr into uart_amba_port > -Run checkpatch with no error or warning > > Changes in v2: > -Fix two compilation errors > > drivers/tty/serial/amba-pl011.c | 38 ++++++++++++++++++++++++++++++++++++++ > 1 file changed, 38 insertions(+) > > diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c > index c255476..026add3 100644 > --- a/drivers/tty/serial/amba-pl011.c > +++ b/drivers/tty/serial/amba-pl011.c > @@ -44,6 +44,7 @@ > > #include "amba-pl011.h" > > +#define ISEMPTY 1 > #define UART_NR 14 > > #define SERIAL_AMBA_MAJOR 204 > @@ -264,6 +265,7 @@ struct uart_amba_port { > unsigned int fifosize; /* vendor-specific */ > unsigned int old_cr; /* state during shutdown */ > unsigned int fixed_baud; /* vendor-set fixed baud rate */ > + unsigned int cr; > char type[12]; > #ifdef CONFIG_DMA_ENGINE > /* DMA stuff */ > @@ -1284,14 +1286,33 @@ static inline bool pl011_dma_rx_running(struct uart_amba_port *uap) > #define pl011_dma_flush_buffer NULL > #endif > > +static unsigned int pl011_tx_empty(struct uart_port *port); > + > static void pl011_stop_tx(struct uart_port *port) > { > + unsigned int count = 1000000; /* 1s */ 1 second of what? > struct uart_amba_port *uap = > container_of(port, struct uart_amba_port, port); > > uap->im &= ~UART011_TXIM; > pl011_write(uap->im, uap, REG_IMSC); > pl011_dma_tx_stop(uap); > + if (port->rs485.flags & SER_RS485_ENABLED) { > + while(pl011_tx_empty(port) != ISEMPTY && count) { > + count--; > + cpu_relax(); > + udelay(1); Why relax and delay? And always run checkpatch on your change before sending it out next time. thanks, greg k-h