From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.19]) (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 743B716C684; Fri, 7 Feb 2025 09:20:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.19 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738920044; cv=none; b=Um6CpGgH1ecv/1q4GiLx4oX68QJd3okXx6EnQ+o2v+is9DIbAjiSwP34m2mEqh68fZQndjJiBvgZz//bDsQFdJoTS3iE6XYPeTW1rwMeqwqOmT+3vW20tHG7fR3xjfzTayaCzWeiFujUHf5xCiBnwOcm2VvohqJWIU00ZzoXSJc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738920044; c=relaxed/simple; bh=hA2SG/by2VlZkg0k+rBAIateDa8Wr9F6Pl3v/Hw6QSU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=SubGo9z5pVQ5wUQ+ChjUmebZtagaSlMmfBMZHrHxIJ1M2vnZo4L8O3HtlgtDjXh8rM/up5LS1RSfxVzWOkjMAwhyvXFDilGCLA6RnQj9w3b+qoNu1h6FMFrwawhTyV4l18iNyRsKumlINSK6gCqP8NDM4G8tRZ58gXukiTjML1M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=fZWljDPb; arc=none smtp.client-ip=198.175.65.19 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="fZWljDPb" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1738920042; x=1770456042; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=hA2SG/by2VlZkg0k+rBAIateDa8Wr9F6Pl3v/Hw6QSU=; b=fZWljDPb6Dt6BamXlxUgRg/BGeXNvgwfCEJrECIl1AXkmStsvGBxXdd6 KiBxMDtqf9ELAwe1i3PNFA3SNtfNmIzaQqSSgPrORD+dsHDCSyHT1Zn72 JvlDEBWozaeJIZwr3xE0ARQdDERWMQwCBmVejzG3Oy1PSqvuq19DOtQhA RVjFdS7fgoyNQ1TI3+SEny5dqfXkvTMv8zT0n3tgO/G8XN4rxdauo7zhx S/cWcvohZKvHGC7YtNGEzEKwR4N2hEHyudg1KuigqRKFhQ6IaAyHf/JS1 71oGDga8WKNrWhqV11+sDQ3MDKNj9eovKdIsekPibuJSy8vQ1qW1mtKkA g==; X-CSE-ConnectionGUID: Sfb1Be4gSV6/KJUHXJ31Vw== X-CSE-MsgGUID: qX5FiCzlRuCILTKoPOQATg== X-IronPort-AV: E=McAfee;i="6700,10204,11336"; a="39428950" X-IronPort-AV: E=Sophos;i="6.13,266,1732608000"; d="scan'208";a="39428950" Received: from orviesa001.jf.intel.com ([10.64.159.141]) by orvoesa111.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Feb 2025 01:20:40 -0800 X-CSE-ConnectionGUID: Rs/q4v6kTrSfo8mlMCbvMQ== X-CSE-MsgGUID: 4DBwnz/7TVqAchVWKhRZfg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.12,224,1728975600"; d="scan'208";a="148692076" Received: from choongyo-mobl.gar.corp.intel.com (HELO [10.247.39.73]) ([10.247.39.73]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Feb 2025 01:20:32 -0800 Message-ID: <564ede5d-9f53-40be-9305-63f63b384e15@linux.intel.com> Date: Fri, 7 Feb 2025 17:20:29 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next v7 2/7] net: pcs: xpcs: re-initiate clause 37 Auto-negotiation To: "Russell King (Oracle)" Cc: Simon Horman , Jose Abreu , Jose Abreu , David E Box , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H . Peter Anvin" , Rajneesh Bhardwaj , David E Box , Andrew Lunn , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Maxime Coquelin , Alexandre Torgue , Jiawen Wu , Mengyuan Lou , Heiner Kallweit , Hans de Goede , =?UTF-8?Q?Ilpo_J=C3=A4rvinen?= , Richard Cochran , Serge Semin , x86@kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, platform-driver-x86@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org References: <20250206131859.2960543-1-yong.liang.choong@linux.intel.com> <20250206131859.2960543-3-yong.liang.choong@linux.intel.com> Content-Language: en-US From: Choong Yong Liang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 6/2/2025 11:30 pm, Russell King (Oracle) wrote: > On Thu, Feb 06, 2025 at 09:18:54PM +0800, Choong Yong Liang wrote: >> The xpcs_switch_interface_mode function was introduced to handle >> interface switching. >> >> According to the XPCS datasheet, a soft reset is required to initiate >> Clause 37 auto-negotiation when the XPCS switches interface modes. > > Hmm. Given that description, taking it literally, claus 37 > auto-negotiation is 1000BASE-X, not Cisco SGMII (which isn't an IEEE > 802.3 standard.) Are you absolutely sure that this applies to Cisco > SGMII? > Hi Russell, Yes, you are correct that Clause 37 auto-negotiation is for 1000BASE-X. However, I do not believe it applies to Cisco SGMII. The XPCS implements Clause 37 auto-negotiation for both 1000BASE-X and SGMII. > If the reset is required when switching to SGMII, should it be done > before or after configuring the XPCS for SGMII? > A soft reset is required before configuring the XPCS for SGMII. Based on the existing XPCS handling in the initial state, the xpcs_create() function will be called, and then xpcs->need_reset will be set to true. Later on, phylink_major_config() will call xpcs_pre_config() to perform the xpcs_soft_reset(), and then it will continue with xpcs_config(). I apologize for missing this patch: https://patchwork.kernel.org/project/netdevbpf/patch/E1svfMA-005ZI3-Va@rmk-PC.armlinux.org.uk/ I think I should move xpcs_switch_interface_mode() to xpcs_pre_config() and just update xpcs->need_reset instead of implementing my own method for calling xpcs_soft_reset(). > Also, if the reset is required, what happens if we're already using > SGMII, but AN has been disabled temporarily and is then re-enabled? > Is a reset required? > Good point. I cannot find this scenario in the datasheet. Please allow me some time to test this scenario. I will update you with the results. > What about 1000BASE-X when AN is enabled or disabled and then switching > to SGMII? > According to the datasheet, a soft reset is required. >> +static int xpcs_switch_to_aneg_c37_sgmii(const struct dw_xpcs_compat *compat, >> + struct dw_xpcs *xpcs, >> + unsigned int neg_mode) >> +{ >> + bool an_c37_enabled; >> + int ret, mdio_ctrl; >> + >> + if (neg_mode == PHYLINK_PCS_NEG_INBAND_ENABLED) { >> + mdio_ctrl = xpcs_read(xpcs, MDIO_MMD_VEND2, MII_BMCR); >> + if (mdio_ctrl < 0) >> + return mdio_ctrl; >> + >> + an_c37_enabled = mdio_ctrl & BMCR_ANENABLE; >> + if (!an_c37_enabled) { > > I don't think that we need "an_c37_enabled" here, I think simply: > > if (!(mdio_ctrl & BMCR_ANENABLE)) { > > would be sufficient. > >> + //Perform soft reset to initiate C37 auto-negotiation >> + ret = xpcs_soft_reset(xpcs, compat); >> + if (ret) >> + return ret; >> + } >> + } >> + return 0; > > I'm also wondering (as above) whether this soft reset needs to happen > _after_ xpcs_config_aneg_c37_sgmii() has done its work - this function > temporarily disables AN while it's doing its work. > Based on the programming sequence in the datasheet, it is not necessary to perform a soft reset after xpcs_config_aneg_c37_sgmii() has completed its work. > I'm also wondering whether AN being disabled is really a deciding > factor (e.g. when switching from 1000BASE-X AN-enabled to SGMII, is a > reset required?) > Thank you for pointing this out. The datasheet only mentions performing a soft reset when switching to the 1000BASE-X and SGMII interfaces, and it does not specify whether AN needs to be enabled or disabled. I thought adding a check would reduce the calls to the soft reset. However, I did not consider the scenario of switching from 1000BASE-X with AN enabled to SGMII with AN enabled. This scenario might cause regression. I will remove all the checks and just perform a soft reset when switching to the SGMII interface.