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 phobos.denx.de (phobos.denx.de [85.214.62.61]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 2502EC4321E for ; Mon, 5 Dec 2022 06:20:45 +0000 (UTC) Received: from h2850616.stratoserver.net (localhost [IPv6:::1]) by phobos.denx.de (Postfix) with ESMTP id BEF25854FD; Mon, 5 Dec 2022 07:20:43 +0100 (CET) Authentication-Results: phobos.denx.de; dmarc=none (p=none dis=none) header.from=denx.de Authentication-Results: phobos.denx.de; spf=pass smtp.mailfrom=u-boot-bounces@lists.denx.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=denx.de; s=phobos-20191101; t=1670221243; bh=x/kYXJs/kOcSkoi+bhip5cQHYuDjvvidJP0of+bDIDQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From; b=HwEvGoGhffE3BKCJMW/SPoQbF4WQJhTnTIpwISAvuShm5QqwwgVkWcx9+jF1BGVDs OVnOzJtOV6ingrz3w4nqSUA9yHlQiK624LeZFPW1xMYgSif5OqRayGMiHUAUJ13rsw ieiFSVmxLD8ppKAFOgf5rDJ1UNbAM0BJhfmFGoQFfQkL00Gp6ucHubOEA6VlfbQnAN Wt5aZd0mBMujxJBwi37C0fljXxFQeJJWtS6NvLDZwvhrMHjQuR1CRkqMVFUYhA5u/n WufJgdYy8b5fEwafT5EJOciBPKgEAoOqJ6bP7hEtdePzyXzprU0XXx7wYX56FReJ4v TBkMgCigWNjzQ== Received: by phobos.denx.de (Postfix, from userid 109) id 52839854FD; Mon, 5 Dec 2022 07:20:42 +0100 (CET) Received: from mout-u-107.mailbox.org (mout-u-107.mailbox.org [80.241.59.207]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (No client certificate requested) by phobos.denx.de (Postfix) with ESMTPS id 033DC85507 for ; Mon, 5 Dec 2022 07:20:40 +0100 (CET) Authentication-Results: phobos.denx.de; dmarc=none (p=none dis=none) header.from=denx.de Authentication-Results: phobos.denx.de; spf=fail smtp.mailfrom=sr@denx.de Received: from smtp102.mailbox.org (smtp102.mailbox.org [10.196.197.102]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-384) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mout-u-107.mailbox.org (Postfix) with ESMTPS id 4NQYM54pF6z9sTg; Mon, 5 Dec 2022 07:20:33 +0100 (CET) Message-ID: <279515f2-0bd3-8b1d-7bad-9b4cbc9e0efa@denx.de> Date: Mon, 5 Dec 2022 07:20:28 +0100 MIME-Version: 1.0 Subject: Re: [PATCH] serial: Use -EAGAIN in getc and putc To: =?UTF-8?Q?Pali_Roh=c3=a1r?= Cc: u-boot@lists.denx.de, Simon Glass References: <20221204123655.29939-1-pali@kernel.org> Content-Language: en-US From: Stefan Roese In-Reply-To: <20221204123655.29939-1-pali@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-BeenThere: u-boot@lists.denx.de X-Mailman-Version: 2.1.39 Precedence: list List-Id: U-Boot discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: u-boot-bounces@lists.denx.de Sender: "U-Boot" X-Virus-Scanned: clamav-milter 0.103.6 at phobos.denx.de X-Virus-Status: Clean On 12/4/22 13:36, Pali Rohár wrote: > U-Boot serial code already handles -EAGAIN value from getc and putc > callbacks. So change drivers code to return -EAGAIN when HW is busy instead > of doing its own busy loop and waiting until HW is ready. > > Signed-off-by: Pali Rohár Reviewed-by: Stefan Roese Thanks, Stefan > --- > drivers/serial/serial_arc.c | 8 ++++---- > drivers/serial/serial_lpuart.c | 8 ++++---- > drivers/serial/serial_mvebu_a3700.c | 8 ++++---- > 3 files changed, 12 insertions(+), 12 deletions(-) > > diff --git a/drivers/serial/serial_arc.c b/drivers/serial/serial_arc.c > index b2d95bdbe18d..c2fc8a901e25 100644 > --- a/drivers/serial/serial_arc.c > +++ b/drivers/serial/serial_arc.c > @@ -53,8 +53,8 @@ static int arc_serial_putc(struct udevice *dev, const char c) > struct arc_serial_plat *plat = dev_get_plat(dev); > struct arc_serial_regs *const regs = plat->reg; > > - while (!(readb(®s->status) & UART_TXEMPTY)) > - ; > + if (!(readb(®s->status) & UART_TXEMPTY)) > + return -EAGAIN; > > writeb(c, ®s->data); > > @@ -83,8 +83,8 @@ static int arc_serial_getc(struct udevice *dev) > struct arc_serial_plat *plat = dev_get_plat(dev); > struct arc_serial_regs *const regs = plat->reg; > > - while (!arc_serial_tstc(regs)) > - ; > + if (!arc_serial_tstc(regs)) > + return -EAGAIN; > > /* Check for overflow errors */ > if (readb(®s->status) & UART_OVERFLOW_ERR) > diff --git a/drivers/serial/serial_lpuart.c b/drivers/serial/serial_lpuart.c > index ff576da516d4..d7259d531b55 100644 > --- a/drivers/serial/serial_lpuart.c > +++ b/drivers/serial/serial_lpuart.c > @@ -168,8 +168,8 @@ static void _lpuart_serial_setbrg(struct udevice *dev, > static int _lpuart_serial_getc(struct lpuart_serial_plat *plat) > { > struct lpuart_fsl *base = plat->reg; > - while (!(__raw_readb(&base->us1) & (US1_RDRF | US1_OR))) > - schedule(); > + if (!(__raw_readb(&base->us1) & (US1_RDRF | US1_OR))) > + return -EAGAIN; > > barrier(); > > @@ -181,8 +181,8 @@ static void _lpuart_serial_putc(struct lpuart_serial_plat *plat, > { > struct lpuart_fsl *base = plat->reg; > > - while (!(__raw_readb(&base->us1) & US1_TDRE)) > - schedule(); > + if (!(__raw_readb(&base->us1) & US1_TDRE)) > + return -EAGAIN; > > __raw_writeb(c, &base->ud); > } > diff --git a/drivers/serial/serial_mvebu_a3700.c b/drivers/serial/serial_mvebu_a3700.c > index 0fcd7e88acee..b2017c645565 100644 > --- a/drivers/serial/serial_mvebu_a3700.c > +++ b/drivers/serial/serial_mvebu_a3700.c > @@ -40,8 +40,8 @@ static int mvebu_serial_putc(struct udevice *dev, const char ch) > struct mvebu_plat *plat = dev_get_plat(dev); > void __iomem *base = plat->base; > > - while (readl(base + UART_STATUS_REG) & UART_STATUS_TXFIFO_FULL) > - ; > + if (readl(base + UART_STATUS_REG) & UART_STATUS_TXFIFO_FULL) > + return -EAGAIN; > > writel(ch, base + UART_TX_REG); > > @@ -53,8 +53,8 @@ static int mvebu_serial_getc(struct udevice *dev) > struct mvebu_plat *plat = dev_get_plat(dev); > void __iomem *base = plat->base; > > - while (!(readl(base + UART_STATUS_REG) & UART_STATUS_RX_RDY)) > - ; > + if (!(readl(base + UART_STATUS_REG) & UART_STATUS_RX_RDY)) > + return -EAGAIN; > > return readl(base + UART_RX_REG) & 0xff; > } Viele Grüße, Stefan Roese -- DENX Software Engineering GmbH, Managing Director: Erika Unter HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-51 Fax: (+49)-8142-66989-80 Email: sr@denx.de