From: "Wells Lu 呂芳騰" <wells.lu@sunplus.com>
To: Andrew Lunn <andrew@lunn.ch>
Cc: "Wells Lu" <wellslutw@gmail.com>,
"davem@davemloft.net" <davem@davemloft.net>,
"kuba@kernel.org" <kuba@kernel.org>,
"robh+dt@kernel.org" <robh+dt@kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"p.zabel@pengutronix.de" <p.zabel@pengutronix.de>,
"Vincent Shih 施錕鴻" <vincent.shih@sunplus.com>
Subject: RE: [PATCH v2 2/2] net: ethernet: Add driver for Sunplus SP7021
Date: Fri, 26 Nov 2021 16:12:46 +0000 [thread overview]
Message-ID: <38e40bc4c0de409ca959bcb847c1fc96@sphcmbx02.sunplus.com.tw> (raw)
In-Reply-To: <YaDxc2+HKUYxsmX4@lunn.ch>
Hi Andrew,
From data provided by ASIC engineer, MAC of SP7021 only
reads the 4 registers of PHY:
0: Control register
1: Status register
4: Auto-negotiation advertisement register
5: Auto-negotiation link partner ability register
It does not read any other registers of PHY.
Best regards,
Wells Lu
> > Hi Andrew,
> >
> > I set phy-id registers to 30 and 31 and found the read-back values of
> > mdio read commands from CPU are all 0x0000.
> >
> > I consulted with an ASIC engineer. She confirmed that if phy-id of a
> > mdio command from CPU does not match any phy-id registers, the mdio
> > command will not be sent out.
> >
> > She explained if phy-id of a mdio command does not match any phy-id
> > registers (represent addresses of external PHYs), why MAC needs to
> > send a command to non-existing PHY?
>
> Reads or writes on a real PHY which Linux is driving can have side effects. There is a
> link statue register which latches. Read it once, you get the last status, read it again,
> you get the current status. If the MAC hardware is reading this register as well a Linux,
> bad things will happen. A read on the interrupt status register often clears the interrupts.
> So Linux will not see the interrupts.
>
> So you need to make sure you hardware is not touching a PHY which Linux uses. Which is
> why i suggested using MDIO bus address 31, which generally does not have a PHY at that
> address.
>
> Andrew
next prev parent reply other threads:[~2021-11-26 16:15 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-03 11:02 [PATCH 0/2] This is a patch series of ethernet driver for Sunplus SP7021 SoC Wells Lu
2021-11-03 11:02 ` [PATCH 1/2] devicetree: bindings: net: Add bindings doc for Sunplus SP7021 Wells Lu
2021-11-03 11:02 ` [PATCH 2/2] net: ethernet: Add driver " Wells Lu
2021-11-03 12:05 ` Denis Kirjanov
2021-11-03 14:08 ` Wells Lu 呂芳騰
2021-11-03 12:10 ` Philipp Zabel
2021-11-03 15:11 ` Wells Lu 呂芳騰
2021-11-03 15:52 ` Randy Dunlap
2021-11-03 18:08 ` Wells Lu 呂芳騰
2021-11-03 19:30 ` Andrew Lunn
2021-11-04 5:31 ` Wells Lu 呂芳騰
2021-11-04 12:59 ` Andrew Lunn
2021-11-04 14:55 ` Randy Dunlap
2021-11-04 17:51 ` Wells Lu 呂芳騰
2021-11-04 17:46 ` Wells Lu 呂芳騰
2021-11-04 18:21 ` Andrew Lunn
2021-11-04 19:03 ` Wells Lu 呂芳騰
2021-11-03 20:26 ` Randy Dunlap
2021-11-03 16:51 ` Andrew Lunn
2021-11-05 11:25 ` Wells Lu 呂芳騰
2021-11-05 13:37 ` Andrew Lunn
2021-11-08 9:37 ` Wells Lu 呂芳騰
2021-11-08 13:15 ` Andrew Lunn
2021-11-08 14:26 ` Wells Lu 呂芳騰
2021-11-08 14:52 ` Andrew Lunn
2021-11-08 16:47 ` Wells Lu 呂芳騰
2021-11-08 17:32 ` Andrew Lunn
2021-11-09 14:39 ` Wells Lu 呂芳騰
2021-11-09 15:32 ` Andrew Lunn
2021-11-09 17:05 ` Wells Lu 呂芳騰
2021-11-14 19:19 ` Pavel Skripkin
2021-11-17 9:28 ` Wells Lu 呂芳騰
2021-11-03 11:27 ` [PATCH 0/2] This is a patch series of ethernet driver for Sunplus SP7021 SoC Denis Kirjanov
2021-11-11 9:04 ` [PATCH v2 0/2] This is a patch series for pinctrl " Wells Lu
2021-11-11 9:04 ` [PATCH v2 1/2] devicetree: bindings: net: Add bindings doc for Sunplus SP7021 Wells Lu
2021-11-11 14:57 ` Rob Herring
2021-11-12 2:57 ` Wells Lu 呂芳騰
2021-11-11 18:23 ` Andrew Lunn
2021-11-12 2:50 ` Wells Lu 呂芳騰
2021-11-11 9:04 ` [PATCH v2 2/2] net: ethernet: Add driver " Wells Lu
2021-11-11 11:31 ` Denis Kirjanov
2021-11-13 14:22 ` Wells Lu 呂芳騰
2021-11-13 15:34 ` Andrew Lunn
2021-11-18 8:15 ` Wells Lu 呂芳騰
2021-11-12 17:42 ` kernel test robot
2021-11-12 23:16 ` Florian Fainelli
2021-11-12 23:24 ` Andrew Lunn
2021-11-15 14:38 ` Wells Lu 呂芳騰
2021-11-14 18:59 ` Wells Lu 呂芳騰
2021-11-12 23:58 ` Andrew Lunn
2021-11-16 17:09 ` Wells Lu 呂芳騰
2021-11-16 22:15 ` Andrew Lunn
2021-11-18 8:22 ` Wells Lu 呂芳騰
2021-11-25 11:28 ` Wells Lu 呂芳騰
2021-11-25 15:20 ` Andrew Lunn
2021-11-26 3:56 ` Wells Lu 呂芳騰
2021-11-26 14:38 ` Andrew Lunn
2021-11-26 16:12 ` Wells Lu 呂芳騰 [this message]
2021-11-26 18:07 ` Andrew Lunn
2021-11-26 19:13 ` Wells Lu 呂芳騰
2021-11-26 19:32 ` Andrew Lunn
2021-11-29 11:16 ` Wells Lu 呂芳騰
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