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 83303946B for ; Fri, 9 Jun 2023 07:37:37 +0000 (UTC) Received: from relay6-d.mail.gandi.net (relay6-d.mail.gandi.net [217.70.183.198]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 787C3359A; Fri, 9 Jun 2023 00:37:25 -0700 (PDT) X-GND-Sasl: maxime.chevallier@bootlin.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1686296243; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=2ihOk65xfSsNkRNf3ryEGeanTlCCQd6nVcfq+SRlpTg=; b=gRBXEFH0TDa5+UcCAUk/+XG/gckNlFc1ozs+iKHc0rPNB4EDMqCnMbDDWr3fL+Jzzi+pi6 SJKv/wkMGCuLX6wANaOWTBGiJB6478ZSzL/xRCM116XgoEv3sn+d8otQAMD/1QCWte7ovA T+yBNaFZLdR8jHCfWp4ojURcdOY4trG/GPVFc7d3Py3DXkAfsyGyNhukv8EUbygkv9l+OR dUW5zOWcM8HL5gJ0IzEDt5xow4UwnA6A+fYbmXa/ES8WBA6me6InfutFioWt4K0ed/I3g8 w0geq4/muiZjjqV8/WdqdGjRYl9k0UA7+f0phCGrV7KC6JEbcpS0sz6fGeaPFA== X-GND-Sasl: maxime.chevallier@bootlin.com X-GND-Sasl: maxime.chevallier@bootlin.com X-GND-Sasl: maxime.chevallier@bootlin.com X-GND-Sasl: maxime.chevallier@bootlin.com X-GND-Sasl: maxime.chevallier@bootlin.com X-GND-Sasl: maxime.chevallier@bootlin.com X-GND-Sasl: maxime.chevallier@bootlin.com X-GND-Sasl: maxime.chevallier@bootlin.com X-GND-Sasl: maxime.chevallier@bootlin.com X-GND-Sasl: maxime.chevallier@bootlin.com X-GND-Sasl: maxime.chevallier@bootlin.com X-GND-Sasl: maxime.chevallier@bootlin.com Received: by mail.gandi.net (Postfix) with ESMTPSA id 4D4F1C0005; Fri, 9 Jun 2023 07:37:21 +0000 (UTC) Date: Fri, 9 Jun 2023 10:09:12 +0200 From: Maxime Chevallier To: "Russell King (Oracle)" Cc: davem@davemloft.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, thomas.petazzoni@bootlin.com, Andrew Lunn , Florian Fainelli , Heiner Kallweit , linux-arm-kernel@lists.infradead.org, Horatiu.Vultur@microchip.com, Allan.Nielsen@microchip.com, UNGLinuxDriver@microchip.com, Vladimir Oltean Subject: Re: [PATCH net 2/2] net: phylink: use USXGMII control-word format to parse Q-USGMII word Message-ID: <20230609100912.70a2bbc1@pc-7.home> In-Reply-To: References: <20230608163415.511762-1-maxime.chevallier@bootlin.com> <20230608163415.511762-4-maxime.chevallier@bootlin.com> <20230608195330.476fca86@pc-7.home> Organization: Bootlin X-Mailer: Claws Mail 4.1.1 (GTK 3.24.37; x86_64-redhat-linux-gnu) 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-Transfer-Encoding: 7bit X-Spam-Status: No, score=-2.8 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H5,RCVD_IN_MSPIKE_WL,SPF_HELO_NONE,SPF_PASS, T_SCC_BODY_TEXT_LINE,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Hi Russell, On Thu, 8 Jun 2023 18:30:41 +0100 "Russell King (Oracle)" wrote: > On Thu, Jun 08, 2023 at 07:53:30PM +0200, Maxime Chevallier wrote: > > Hi Russell, > > > > On Thu, 8 Jun 2023 17:32:52 +0100 > > "Russell King (Oracle)" wrote: > > > > > On Thu, Jun 08, 2023 at 06:34:15PM +0200, Maxime Chevallier wrote: > > > > diff --git a/include/uapi/linux/mdio.h b/include/uapi/linux/mdio.h > > > > index 256b463e47a6..1d20a9082507 100644 > > > > --- a/include/uapi/linux/mdio.h > > > > +++ b/include/uapi/linux/mdio.h > > > > @@ -444,4 +444,7 @@ static inline __u16 mdio_phy_id_c45(int prtad, int devad) > > > > #define MDIO_USXGMII_5000FULL 0x1a00 /* 5000Mbps full-duplex */ > > > > #define MDIO_USXGMII_LINK 0x8000 /* PHY link with copper-side partner */ > > > > > > > > +/* Usgmii control word is based on Usxgmii, masking away 2.5, 5 and 10Gbps */ > > > > +#define MDIO_USGMII_SPD_MASK 0x0600 > > > > > > This isn't correct: > > > > > > 11:9 Speed: Bit 11, 10, 9: > > > 1 1 1 to 011 = Reserved > > > 0 1 0 = 1000 Mbps: 1000BASE-TX, 1000BASE-X > > > 0 0 1 = 100 Mbps: 100BASE-TX, 100BASE-FX > > > 0 0 0 = 10 Mbps: 10BASET, 10BASE2, 10BASE5 > > > > > > If we only look at bits 10 and 9, then we're interpreting the reserved > > > combinations as valid as well. > > > > That's why I rewrote the decoding helper instead of simply masking away > > the extra bit, so that we exclude the 0 1 1 combination ( 10G speed ). > > I don't think you've understood my comment properly. Here is what > the code is doing: Indeed :( thanks for the clarifications. > +#define MDIO_USGMII_SPD_MASK 0x0600 > + switch (lpa & MDIO_USGMII_SPD_MASK) { > #define MDIO_USXGMII_10 0x0000 /* 10Mbps */ > + case MDIO_USXGMII_10: > + state->speed = SPEED_10; > + break; > #define MDIO_USXGMII_100 0x0200 /* 100Mbps */ > + case MDIO_USXGMII_100: > + state->speed = SPEED_100; > + break; > #define MDIO_USXGMII_1000 0x0400 /* 1000Mbps */ > + case MDIO_USXGMII_1000: > + state->speed = SPEED_1000; > + break; > + default: > + state->link = false; > + return; > + } > > So, this will decode bits 11:9 as: > > 000 10Mbps > 001 100Mbps > 010 1000Mgps > 011 link = false > 100 10Mbps > 101 100Mbps > 110 1000Mbps > 111 link = false > > Whereas, USGMII says the last four are all reserved. Why does this > happen? Because the mask is defined as: > > +#define MDIO_USGMII_SPD_MASK 0x0600 > > which only covers bits 10 and 9, masking off bit 11. However, bit 11 > is _still_ part of the field, and if it's set, then it is a "reserved" > speed. We should not be just ignoring bit 11. > > I hope that helps to clarify. > Indeed, thanks... I'll respin with a proper implementation this time. Thanks for spotting this Maxime