From: Andrew Lunn <andrew@lunn.ch>
To: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Jeremy Linton <jeremy.linton@arm.com>,
netdev@vger.kernel.org, davem@davemloft.net,
f.fainelli@gmail.com, hkallweit1@gmail.com,
madalin.bucur@oss.nxp.com, calvin.johnson@oss.nxp.com,
linux-kernel@vger.kernel.org
Subject: Re: [RFC 08/11] net: phy: Allow mdio buses to auto-probe c45 devices
Date: Mon, 25 May 2020 15:43:47 +0200 [thread overview]
Message-ID: <20200525134347.GA752669@lunn.ch> (raw)
In-Reply-To: <20200525082510.GH1551@shell.armlinux.org.uk>
> > > So i think it would be better to have
> > >
> > > enum {
> > > MDIOBUS_UNKNOWN = 0,
> > > MDIOBUS_C22,
> > > MDIOBUS_C45,
> > > MDIOBUS_C45_C22,
> > > } bus_capabilities;
> > >
> > > Describe just what the bus master can support.
> >
> > Yes, the naming is reasonable and I will update it in the next patch. I went
> > around a bit myself with this naming early on, and the problem I saw was
> > that a C45 capable master, can have C45 electrical phy's that only respond
> > to c22 requests (AFAIK).
>
> If you have a master that can only generate clause 45 cycles, and
> someone is daft enough to connect a clause 22 only PHY to it, the
> result is hardware that doesn't work - there's no getting around
> that. The MDIO interface can't generate the appropriate cycles to
> access the clause 22 PHY. So, this is not something we need care
> about.
>
> > So the MDIOBUS_C45 (I think I was calling it
> > C45_ONLY) is an invalid selection. Not, that it wouldn't be helpful to have
> > a C45_ONLY case, but that the assumption is that you wouldn't try and probe
> > c22 registers, which I thought was a mistake.
>
> MDIOBUS_C45 means "I can generate clause 45 cycles".
> MDIOBUS_C22 means "I can generate clause 22 cycles".
> MDIOBUS_C45_C22 means "I can generate both clause 45 and clause 22
> cycles."
>
> Notice carefully the values these end up with - MDIOBUS_C22 = BIT(0),
> MDIOBUS_C45 = BIT(1), MDIOBUS_C45_C22 = BIT(0) | BIT(1). I suspect
> that was no coincidence in Andrew's suggestion.
Hi Russell
What was a nice side affect. Since i doubt Jeremy is going to go
through every MDIO driver and set the capabilities correctly, i wanted
0 to have a safe meaning. In the code we should treat MDIOBUS_UNKNOWN
and MDIOBUS_C22 identically. But maybe some time in the distant
future, we can make 0 issue a warning.
Andrew
next prev parent reply other threads:[~2020-05-25 13:44 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-22 21:30 [RFC 00/11] Make C45 autoprobe more robust Jeremy Linton
2020-05-22 21:30 ` [RFC 01/11] net: phy: Don't report success if devices weren't found Jeremy Linton
2020-05-23 18:20 ` Russell King - ARM Linux admin
2020-05-25 2:46 ` Jeremy Linton
2020-05-25 9:45 ` Russell King - ARM Linux admin
2020-05-25 21:02 ` Jeremy Linton
2020-05-25 21:07 ` Russell King - ARM Linux admin
2020-05-25 21:59 ` Jeremy Linton
2020-05-22 21:30 ` [RFC 02/11] net: phy: Simplify MMD device list termination Jeremy Linton
2020-05-23 18:36 ` Russell King - ARM Linux admin
2020-05-25 2:48 ` Jeremy Linton
2020-05-25 8:09 ` Russell King - ARM Linux admin
2020-05-22 21:30 ` [RFC 03/11] net: phy: refactor c45 phy identification sequence Jeremy Linton
2020-05-23 15:28 ` Andrew Lunn
2020-05-23 17:16 ` Jeremy Linton
2020-05-23 17:32 ` Jeremy Linton
2020-05-23 19:12 ` Russell King - ARM Linux admin
2020-05-23 18:30 ` Russell King - ARM Linux admin
2020-05-23 19:51 ` Andrew Lunn
2020-05-23 20:01 ` Russell King - ARM Linux admin
2020-05-25 2:37 ` Jeremy Linton
2020-05-22 21:30 ` [RFC 04/11] net: phy: Handle c22 regs presence better Jeremy Linton
2020-05-23 18:37 ` Russell King - ARM Linux admin
2020-05-25 3:34 ` Jeremy Linton
2020-05-25 9:53 ` Russell King - ARM Linux admin
2020-05-25 10:06 ` Russell King - ARM Linux admin
2020-05-25 21:51 ` Jeremy Linton
2020-05-25 22:01 ` Russell King - ARM Linux admin
2020-05-25 22:22 ` Jeremy Linton
2020-05-25 23:09 ` Russell King - ARM Linux admin
2020-05-25 23:22 ` Jeremy Linton
2020-05-25 23:33 ` Russell King - ARM Linux admin
2020-05-25 23:42 ` Jeremy Linton
2020-05-25 23:46 ` Andrew Lunn
2020-05-25 23:57 ` Russell King - ARM Linux admin
2020-05-25 23:16 ` Jeremy Linton
2020-05-25 23:30 ` Russell King - ARM Linux admin
2020-05-25 22:06 ` Andrew Lunn
2020-05-25 22:17 ` Jeremy Linton
2020-05-25 23:06 ` Andrew Lunn
2020-05-25 23:07 ` Russell King - ARM Linux admin
2020-05-25 23:12 ` Andrew Lunn
2020-05-25 23:46 ` Jeremy Linton
2020-05-25 23:47 ` Andrew Lunn
2020-05-22 21:30 ` [RFC 05/11] net: phy: Scan the entire MMD device space Jeremy Linton
2020-05-22 21:30 ` [RFC 06/11] net: phy: Hoist no phy detected state Jeremy Linton
2020-05-22 21:30 ` [RFC 07/11] net: phy: reset invalid phy reads of 0 back to 0xffffffff Jeremy Linton
2020-05-23 18:44 ` Russell King - ARM Linux admin
2020-05-25 4:20 ` Jeremy Linton
2020-05-25 8:20 ` Russell King - ARM Linux admin
2020-05-22 21:30 ` [RFC 08/11] net: phy: Allow mdio buses to auto-probe c45 devices Jeremy Linton
2020-05-24 14:44 ` Andrew Lunn
2020-05-25 4:28 ` Jeremy Linton
2020-05-25 8:25 ` Russell King - ARM Linux admin
2020-05-25 13:43 ` Andrew Lunn [this message]
2020-05-25 22:09 ` Jeremy Linton
2020-05-25 22:41 ` Russell King - ARM Linux admin
2020-05-22 21:30 ` [RFC 09/11] net: phy: Refuse to consider phy_id=0 a valid phy Jeremy Linton
2020-05-22 21:30 ` [RFC 10/11] net: example acpize xgmac_mdio Jeremy Linton
2020-05-23 18:48 ` Russell King - ARM Linux admin
2020-05-22 21:30 ` [RFC 11/11] net: example xgmac enable extended scanning Jeremy Linton
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