Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   <Divya.Koppera@microchip.com>
To:     <andrew@lunn.ch>
CC:     <hkallweit1@gmail.com>, <linux@armlinux.org.uk>,
        <davem@davemloft.net>, <edumazet@google.com>, <kuba@kernel.org>,
        <pabeni@redhat.com>, <netdev@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <UNGLinuxDriver@microchip.com>
Subject: RE: [PATCH net-next] net: phy: micrel: Adding SQI support for lan8814
 phy
Thread-Topic: [PATCH net-next] net: phy: micrel: Adding SQI support for
 lan8814 phy
Thread-Index: AQHYuFmMgzj2knw/J0+AGHw88JSECa3AKZiAgABiu9CAAQr4AIADwxag
Date:   Mon, 29 Aug 2022 05:23:07 +0000
Message-ID: <CO1PR11MB47712F0DBA0490570DFFB572E2769@CO1PR11MB4771.namprd11.prod.outlook.com>
References: <20220825080549.9444-1-Divya.Koppera@microchip.com>
 <YwfvaSFejdtPtZgK@lunn.ch>
 <CO1PR11MB4771E1680E841F91411AE6DFE2759@CO1PR11MB4771.namprd11.prod.outlook.com>
 <YwkiLoZkkl2cVcOT@lunn.ch>
In-Reply-To: <YwkiLoZkkl2cVcOT@lunn.ch>
Accept-Language: en-US
Content-Language: en-US
x-ms-exchange-antispam-messagedata-chunkcount: 1
x-ms-exchange-antispam-messagedata-0: =?us-ascii?Q?dJepmLDayu5xNOgkGZUo0B77aSOdDUs+mR6hKsSAShIwwbs5lXBcYz06C1AG?=
 =?us-ascii?Q?7uVb7gLBBa8pAkqqpVTdbX7ZUIuoebVd93yGGtERUl6EyGE/jeMpxybLCaSD?=
 =?us-ascii?Q?Hv4iI9DRL6+Xh5AMOP5hcJUNPfJQU1yC/Ipkz9d6zVe7M+4PQdQBAwQ5/JDV?=
 =?us-ascii?Q?D3WY5Bi5Ex2fW6AmvyOkoT5XryZz2zenpefubEBXuh/7ENXWsmGnLMJ5z8DO?=
 =?us-ascii?Q?7NaXV7/8dOMvC1q97x5+5LmqQvM37VOi39e2KDKqUaUyeTpcJTz9khchhbDa?=
 =?us-ascii?Q?ZQekuD6nKDNetUebVNKh+SrbQEuQ94SOMiso3HD53BHhM24TrHRTrbqtj20t?=
 =?us-ascii?Q?I4i7oJsWxN/0fC01HxPDRDQ9EZXEk5hzDO4zTq7GJCfJGYuh0Xcg8nt+Zio0?=
 =?us-ascii?Q?zkSwo8RiZy7jUaH710yMpTS2AOzsnsXkIMGP/SMQ6ej8NGzKyM80tjGKFvSj?=
 =?us-ascii?Q?T6lkATfBKk0JsOZyZaXiXEBHdEmH5inxOHwAL/5iaHOK6AbK+zGQxtyC83kn?=
 =?us-ascii?Q?yY4ykZ3a6/msRbHiRrAGE6nzcKOAYw9WCqmPgOKFlXmYaLZ/671gZ3R43eas?=
 =?us-ascii?Q?znVnmReE8WCC5i1FHDQy9LcxyM0ydV4YH9Ltc2/EWoOweznuiYvSnBuQy9PA?=
 =?us-ascii?Q?u0tcFilZsXE6LstEDGvc8OX1b1qL33/NpMhJ+Qti3YklAh7HDJXN9YbFayCn?=
 =?us-ascii?Q?ye3NO2290NS6HsClloz8HAY0dCNx8ns3P9c7d0pIQtv4geIF8MuRfDlm57t2?=
 =?us-ascii?Q?WPAnD6zoRykBVa0YT6iU6EyC3jTPbV4ejI+y+KsLhjBmx2likY9EfO46GRzc?=
 =?us-ascii?Q?fABr6exMd+KpsKggSViHNIsdR8XlQlxHc4pHYukS5k4jcebmVuPEeb96Hk4Y?=
 =?us-ascii?Q?uS0zcyfAZDYKrj1v8uIpFst+FT4v5IwGbnrKxavlJGNxNZb/9Yz7Q+0IKumW?=
 =?us-ascii?Q?y0S5mT99JkZjwqZx1guSsu5kI6gvyoH6kUEo+3jJH9awGzQ3o0oO68hEcdNM?=
 =?us-ascii?Q?m9El35xFTgvfoXRf+/S2T7ndudX70klIUbYoKmDnXo0pQ4AfdfcsMzruIlPQ?=
 =?us-ascii?Q?PbGVzR6z0l44OHW9Us7ILeIHSZ9qQ++BZqrm1SGVUHEpLPOGNtnYCOZEEPGm?=
 =?us-ascii?Q?fYN2mz3260S2b3e3vuh9BxpINJlS94+oRBLNZejdvPlQDDa0l11xbc93QyjK?=
 =?us-ascii?Q?gCiqxIy3XuXsbUx4Ul9z3GD9/qtMqi8ERO9KpDyoXenVSIBcVGKuhJ0+p/gN?=
 =?us-ascii?Q?H+h80LxsAfq05cH60exKdMyjYKDBF1JTQ42mWJElwSlasQtbJbpCcEUo4INA?=
 =?us-ascii?Q?F2KxBsxfndmdsiFdGumpCBmdR/R+3Wr2eOQSgXuD4OXC3PpseI7MwtZpUthb?=
 =?us-ascii?Q?aku7hGI1Erm7cM2dsT1DnIZN1BVYwzX9C2i8kneIy67+6gOsBtRYk2V8YLOg?=
 =?us-ascii?Q?vwxd8WS6ndGNcv6HB/pikTmTBXaWX1txj7KEVTYrTuPMr2lHeq8Bbwj/TvKN?=
 =?us-ascii?Q?64RYISs9qtwVhTRJgoJ2MBwf0NCAFYuRnPVk47HMibvUhRw/ohO6VdYPs6Ga?=
 =?us-ascii?Q?yNU52HG06gMI7ZjgxyPko9ugQYylyvbkjKQfC3GGqK7WYfZ3u3TUBML9Zg3c?=
 =?us-ascii?Q?Lg=3D=3D?=
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-AuthSource: CO1PR11MB4771.namprd11.prod.outlook.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 6b512745-81c8-4108-4edd-08da897e8e8d
X-MS-Exchange-CrossTenant-originalarrivaltime: 29 Aug 2022 05:23:07.6544
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 3f4057f3-b418-4d4e-ba84-d55b4e897d88
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-CrossTenant-userprincipalname: fhdSxOPNHB/0TdaHloDk8H+m0SX36ZxRT81hMVpNYg+A01xIbWSNXv774TsroijtZqvTazJuAacKu6qcw2DldGwvs/cVACcrxfEyrXIpqCc=
X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ0PR11MB5679
X-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00,DKIM_SIGNED,
        DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED,SPF_HELO_PASS,
        SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no
        version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Hi Andrew,

> -----Original Message-----
> From: Andrew Lunn <andrew@lunn.ch>
> Sent: Saturday, August 27, 2022 1:13 AM
> To: Divya Koppera - I30481 <Divya.Koppera@microchip.com>
> Cc: hkallweit1@gmail.com; linux@armlinux.org.uk; davem@davemloft.net;
> edumazet@google.com; kuba@kernel.org; pabeni@redhat.com;
> netdev@vger.kernel.org; linux-kernel@vger.kernel.org; UNGLinuxDriver
> <UNGLinuxDriver@microchip.com>
> Subject: Re: [PATCH net-next] net: phy: micrel: Adding SQI support for
> lan8814 phy
>=20
> EXTERNAL EMAIL: Do not click links or open attachments unless you know th=
e
> content is safe
>=20
> > > I just took a quick look at the datasheet. It says:
> > >
> >
> > I'm not sure the datasheet you looked into is the right one. Could you
> please crosscheck if its lan8814 or lan8841.
> > Lan8814 is quad port phy where register access are of extended page.
> Lan8841 is 1 port phy where register access are mmd access.
> >
> > > All registers references in this section are in MMD Device Address 1
> > >
> > > So you should be using phy_read_mmd(phydev,
> MDIO_MMD_PMAPMD,
> > > xxx) to read/write these registers. The datasheet i have however is
> > > missing the register map, so i've no idea if it is still 0xe6.
>=20
> https://ww1.microchip.com/downloads/aemDocuments/documents/UNG/
> ProductDocuments/DataSheets/DS-LAN8814-00003592C.pdf
>=20
> 5.13.4 OPEN ALLIANCE TC1/TC12 DCQ SIGNAL QUALITY INDEX
>=20
> Note: All registers references in this section are in MMD Device Address =
1.
>=20

Ah.. I too looked into it. Its a mistake. I suggested for correction of doc=
ument internally. Also requested team to add=20
SQI register set in register document that is published.

> This section defines the implementation of section 6.1.2 of the TC1 and T=
C12
> specifications. This mode builds upon the OPEN Alliance
> TC1/TC12 DCQ Mean Square Error method by mapping the MSE value onto a
> simple quality index. This mode is enabled by setting the sqi_enable bit,=
 in
> the DCQ Configuration register.
>=20
> The MSE value is compared to the thresholds set in the DCQ SQI Table
> Registers to provide an SQI value between 0 (worst value) and 7 (best
> value) as follows:
>=20
> In order to capture the SQI value, the DCQ Read Capture bit in the DCQ
> Configuration register needs to be written as a high with the desired cab=
le
> pair specified in the DCQ Channel Number field of the same register. The
> DCQ Read Capture bit will immediately self-clear and the result will be
> available in the DCQ SQI register.  In addition to the current SQI, the w=
orst
> case (lowest) SQI since the last read is available in the SQI Worst Case =
field.
> The correlation between the SQI values stored in the DCQ SQI register and=
 an
> according Signal to Noise Ratio (SNR) based on Additive White Gaussian
> (AWG) noise (bandwidth of 80 MHz @ 100 Mbps / 550 MHz @ 1000 Mbps) is
> shown in Table 5-5. The bit error rates to be expected in the case of whi=
te
> noise as interference signal is shown in the table as well for informatio=
n
> purposes.
>=20
> I had a quick look at OPEN ALLIANCE specification. It seems to specify ho=
w
> each of these registers should look. It just failed to specify where in t=
he
> address map they are. So if you look at drivers implementing SQI, you see
> most poke around in MDIO_MMD_VEND1.  I wounder if we can actually
> share the implementation between drivers, those that follow the standard,
> with some paramatirisation where the registers are.
>=20

I don't think it will work, each phy may have different register set and ma=
y or may not supports SQI.
Also it contains drivers of too old and that may not support SQI.

Apart from this lan8814 is quad port phy and register set is completely dif=
ferent from other drivers.

>           Andrew

Thanks,
Divya