From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (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 F180D30D03 for ; Tue, 26 Sep 2023 15:47:30 +0000 (UTC) Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [IPv6:2001:4d48:ad52:32c8:5054:ff:fe00:142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 544E71B3 for ; Tue, 26 Sep 2023 08:47:21 -0700 (PDT) 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=dKieqyHLVmbPlA5ShK1WouVOc3ccxmB1XKlRT4o3G6E=; b=1n5GGsmQWeokFpr2FwHGp2QMeM TIajbMVs0haf9T0HEN4Hd0Vp+NZdLMhlQ1QbC/l5Z+jCwU9RDgIgEL9/pflMfevxlUqCaGJ1RJmcD wKdxtFwJ4GOCRApbU+fjKh0WAU/lHTUDgqP+Hi2xhv2yEEQ8IzXy4a1tDe+kDMB1JOq1a3lXmDCiH fZXlOfKbTTnacoMDI+CVkLcJZJVBXZTvu5PqhidHjYAWgZWhUzkS+Y23zvXFl92AmYS2lKe+e1Ybu LLOJJaMNV+9DvDjHYnYUUmmgHgHny9Tk3sIj6qYmO27Zt9kn4onVtcsWLVKDdhk05ZFcqlOIpqMNu e+N49kxg==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:44982) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1qlAHL-0002eC-38; Tue, 26 Sep 2023 16:47:16 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.94.2) (envelope-from ) id 1qlAHL-0000X6-1K; Tue, 26 Sep 2023 16:47:15 +0100 Date: Tue, 26 Sep 2023 16:47:14 +0100 From: "Russell King (Oracle)" To: Serge Semin Cc: Raju Lakkaraju , netdev@vger.kernel.org, davem@davemloft.net, Jose.Abreu@synopsys.com, hkallweit1@gmail.com, UNGLinuxDriver@microchip.com Subject: Re: [PATCH net-next] net: pcs: xpcs: Add 2500BASE-X case in get state for XPCS drivers Message-ID: References: <20230925075142.266026-1-Raju.Lakkaraju@microchip.com> Precedence: bulk X-Mailing-List: netdev@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) X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_BLOCKED, SPF_HELO_NONE,SPF_NONE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net On Tue, Sep 26, 2023 at 06:27:45PM +0300, Serge Semin wrote: > On Tue, Sep 26, 2023 at 03:46:23PM +0100, Russell King (Oracle) wrote: > > On Tue, Sep 26, 2023 at 03:09:47PM +0300, Serge Semin wrote: > > > Hi Russell > > > > > > > Since you have access to the hardware manual, what does it say about > > > > clause 37 auto-negotiation when operating in 2500base-X mode? > > > > > > Here are the parts which mention 37 & SGMII AN in the 2.5G context: > > > > > > 1. "Clause 37 (& SGMII) auto-negotiation is supported in 2.5G mode if > > > the link partner is also operating in the equivalent 2.5G mode." > > > > > > 2. "During the Clause 37/SGMII as the auto-negotiation link timer > > > operates with a faster clock in the 2.5G mode, the timeout duration > > > reduces by a factor of 2.5. To restore the standard specified timeout > > > period, the respective registers must be re-programmed." > > > > > > I guess the entire 2.5G-thing understanding could be generalized by > > > the next sentence from the HW manual: "The 2.5G mode of operation is > > > functionally the same as 1000BASE-X/KX mode, except that the > > > clock-rate is 2.5 times the original rate. In this mode, the > > > Serdes/PHY operates at a serial baud-rate of 3.125 Gbps and DWC_xpcs > > > data-path and the GMII interface to MAC operates at 312.5 MHz (instead > > > of 125 MHz)." Thus here is another info regarding AN in that context: > > > > > > 3. "The DWC_xpcs operates either in 10/100/1000Mbps rate or > > > 25/250/2500Mbps rates respectively with SGMII auto-negotiation. The > > > DWC_xpcs cannot support switching or negotiation between 1G and 2.5G > > > rates using auto-negotiation." > > > > Thanks for the clarification. > > > > So this hardware, just like Marvell hardware, operates 2500BASE-X merely > > by up-clocking, and all the features that were available at 1000BASE-X > > are also available at 2500BASE-X, including the in-band signalling. > > > > Therefore, I think rather than disabling AN outright, the > > PHYLINK_PCS_NEG_* mode passed in should be checked to determine whether > > inband should be used or not. > > Just an additional note which might be relevant in the context of the > DW XPCS 1G/2.5G C37 AN. The C37 auto-negotiation feature will be > unavailable for 1000BASE-X and thus for 2500BASE-X if the IP-core is > synthesized with no support of one. It is determined by the CL37_AN > IP-core synthesize parameter state: > > Enable SGMII Clause 37 | Description: Configures DWC_xpcs to support the > Auto-Negotiation | Clause 37 auto-negotiation > | > | Dependencies: This option is available in the > | following configurations: > | - SUPPORT_1G = Enabled > | - MAIN_MODE = Backplane Ethernet PCS and > | BACKPLANE_ETH_CONFIG = KX_Only or KX4_KX > | or KR_KX or KR_KX4_KX mode > | > | Default Value: Enabled for configurations with > | MAIN_MODE = 1000BASEX-Only PCS and Disabled > | for all other configurations > | > | HDL Parameter Name: CL37_AN > > So depending on the particular (vendor-specific) device configuration > the C37 AN might still unavailable even though the device supports the > 1000BASE-X and 2500BASE-X interfaces. Thanks. I guess there's no way to read the CL37_AN setting from software? -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!