From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [78.32.30.218]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0B4EC2DCF4D; Wed, 3 Dec 2025 09:29:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=78.32.30.218 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764754196; cv=none; b=alMB8YITK+rsYT8H3rB/4hzZvT8M8pptw+usOrnqfOtRcmuxiuv+uUAppqo6WPXjqJiis3lv4t7mU8iIg0UD15EHi0do+6gm7nRebFtgDsGo0zTVDXoIDYhFTIJmUJqDstbrKcI0dd4KgdI4hoIpwJiZzDXX9gnNmaE9NGj62hw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764754196; c=relaxed/simple; bh=ded+QBGC6xLs3khUezFdO4xx+eh/BxqZQHkKWcfOLs8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ueQgn+5pumLKr8UKW2BCwMxI8cugO/fQlw5XYdSlDq4UYEcz8bm++2FIl1Bfr14KZG7Xv1DCNJrSrqKDXVu4ZGjY9dCu3Yhv2c0KBNpzbx0tM+eaGKHWFGBqYmYDOLjaADPVtlc48bOqW4xeb0XfrOrltpJnbvDatGCVuWJTJlw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=armlinux.org.uk; spf=none smtp.mailfrom=armlinux.org.uk; dkim=pass (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b=JwIC1pYJ; arc=none smtp.client-ip=78.32.30.218 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=armlinux.org.uk Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=armlinux.org.uk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="JwIC1pYJ" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=++x36++AQYMYArARypVUnlYPyOBV4DEhIySU5+Og1zY=; b=JwIC1pYJ+kdsaD+CGxDPI7j5sw BXlULWrb7ZSbl4nvGLcVtbK0LSCmgVkgj0xxnriKIzMh0OEOdFju1lo1yi64Dx5ABROZsBHvbTa0r aw63/h/wYHm0d6s7244BN3sYs2OJ9oYU6ZQprlVOM7CSEnMokY7hjcYe2hgzNKs0OmXaRxQpjC5Kf TqeMYHYkY4tjCXEiEerc9o53UadzUXapiRlRnzVoLPdsFuTdf0jMNLetqVfwefSwwk+vEwznb8ajq Lpxg0DHgBz5Z9hDdPwENwpP0NpFM4tBBTalU0SC9t8dx1wSNyzBt3KuVLnnBim1/5LAKVBhq658+M elAMzHbQ==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:54368) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1vQjB6-000000002PY-1BLE; Wed, 03 Dec 2025 09:29:40 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.98.2) (envelope-from ) id 1vQjB2-000000008LC-04oA; Wed, 03 Dec 2025 09:29:36 +0000 Date: Wed, 3 Dec 2025 09:29:35 +0000 From: "Russell King (Oracle)" To: Andrew Lunn Cc: Daniel Golle , Vladimir Oltean , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Simon Horman , netdev@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Frank Wunderlich , Avinash Jayaraman , Bing tao Xu , Liang Xu , Juraj Povazanec , "Fanni (Fang-Yi) Chan" , "Benny (Ying-Tsan) Weng" , "Livia M. Rosu" , John Crispin Subject: Re: [PATCH RFC net-next 3/3] net: dsa: add basic initial driver for MxL862xx switches Message-ID: References: Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: Russell King (Oracle) On Wed, Dec 03, 2025 at 03:07:20AM +0100, Andrew Lunn wrote: > > +/** > > + * struct mxl862xx_ss_sp_tag > > + * @pid: port ID (1~16) > > + * @mask: bit value 1 to indicate valid field > > + * 0 - rx > > + * 1 - tx > > + * 2 - rx_pen > > + * 3 - tx_pen > > + * @rx: RX special tag mode > > + * 0 - packet does NOT have special tag and special tag is NOT inserted > > + * 1 - packet does NOT have special tag and special tag is inserted > > + * 2 - packet has special tag and special tag is NOT inserted > > + * @tx: TX special tag mode > > + * 0 - packet does NOT have special tag and special tag is NOT removed > > + * 1 - packet has special tag and special tag is replaced > > + * 2 - packet has special tag and special tag is NOT removed > > + * 3 - packet has special tag and special tag is removed > > + * @rx_pen: RX special tag info over preamble > > + * 0 - special tag info inserted from byte 2 to 7 are all 0 > > + * 1 - special tag byte 5 is 16, other bytes from 2 to 7 are 0 > > + * 2 - special tag byte 5 is from preamble field, others are 0 > > + * 3 - special tag byte 2 to 7 are from preabmle field > > + * @tx_pen: TX special tag info over preamble > > + * 0 - disabled > > + * 1 - enabled > > + */ > > +struct mxl862xx_ss_sp_tag { > > + u8 pid; > > + u8 mask; > > + u8 rx; > > + u8 tx; > > + u8 rx_pen; > > + u8 tx_pen; > > +} __packed; > > + > > +/** > > + * enum mxl862xx_logical_port_mode - Logical port mode > > + * @MXL862XX_LOGICAL_PORT_8BIT_WLAN: WLAN with 8-bit station ID > > + * @MXL862XX_LOGICAL_PORT_9BIT_WLAN: WLAN with 9-bit station ID > > + * @MXL862XX_LOGICAL_PORT_GPON: GPON OMCI context > > + * @MXL862XX_LOGICAL_PORT_EPON: EPON context > > + * @MXL862XX_LOGICAL_PORT_GINT: G.INT context > > + * @MXL862XX_LOGICAL_PORT_OTHER: Others > > + */ > > +enum mxl862xx_logical_port_mode { > > + MXL862XX_LOGICAL_PORT_8BIT_WLAN = 0, > > + MXL862XX_LOGICAL_PORT_9BIT_WLAN, > > + MXL862XX_LOGICAL_PORT_GPON, > > + MXL862XX_LOGICAL_PORT_EPON, > > + MXL862XX_LOGICAL_PORT_GINT, > > + MXL862XX_LOGICAL_PORT_OTHER = 0xFF, > > +}; > > + > > +/** > > + * struct mxl862xx_ctp_port_assignment - CTP Port Assignment/association with logical port > > + * @logical_port_id: Logical Port Id. The valid range is hardware dependent > > + * @first_ctp_port_id: First CTP Port ID mapped to above logical port ID > > + * @number_of_ctp_port: Total number of CTP Ports mapped above logical port ID > > + * @mode: See &enum mxl862xx_logical_port_mode > > + * @bridge_port_id: Bridge ID (FID) > > + */ > > +struct mxl862xx_ctp_port_assignment { > > + u8 logical_port_id; > > + __le16 first_ctp_port_id; > > + __le16 number_of_ctp_port; > > + enum mxl862xx_logical_port_mode mode; > > + __le16 bridge_port_id; > > +} __packed; > > Does the C standard define the size of an enum? Do you assume this is > a byte? It does not. Some architectures are allowed to choose the storage size of enum depending on the range of values. > > +static int mxl862xx_send_cmd(struct mxl862xx_priv *dev, u16 cmd, u16 size, > > + s16 *presult) > > +{ > > + int ret; > > + > > + ret = __mdiobus_c45_write(dev->bus, dev->sw_addr, MXL862XX_MMD_DEV, > > + MXL862XX_MMD_REG_LEN_RET, size); > > + if (ret) > > + return ret; > > + > > + ret = __mdiobus_c45_write(dev->bus, dev->sw_addr, MXL862XX_MMD_DEV, > > + MXL862XX_MMD_REG_CTRL, cmd | CTRL_BUSY_MASK); > > + if (ret) > > + return ret; > > + > > + ret = mxl862xx_busy_wait(dev); > > + if (ret) > > + return ret; > > + > > + ret = __mdiobus_c45_read(dev->bus, dev->sw_addr, MXL862XX_MMD_DEV, > > + MXL862XX_MMD_REG_LEN_RET); > > + if (ret < 0) > > + return ret; Error codes go via this path. > > + > > + *presult = ret; Register values via this, and if the sign bit is set, *presult is negative. > > + ret = mxl862xx_send_cmd(priv, cmd, size, &result); > > + if (ret < 0) > > + goto out; > > + > > + if (result < 0) { > > + ret = result; > > + goto out; > > + } > > If i'm reading mxl862xx_send_cmd() correct, result is the value of a > register. It seems unlikely this is a Linux error code? result here is the register value, and a negative value is the value from the register. So I agree - this assigns a register value to "ret" which gets promoted from s16 to int (sign extension) and thus gets returned as a Linux error code. So yes, this doesn't seem right. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!