From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: Jeremy Linton <jeremy.linton@arm.com>
Cc: netdev@vger.kernel.org, davem@davemloft.net, andrew@lunn.ch,
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 07/11] net: phy: reset invalid phy reads of 0 back to 0xffffffff
Date: Mon, 25 May 2020 09:20:45 +0100 [thread overview]
Message-ID: <20200525082045.GG1551@shell.armlinux.org.uk> (raw)
In-Reply-To: <d6d71908-58a0-96c9-b046-9a4739cc7bcd@arm.com>
On Sun, May 24, 2020 at 11:20:01PM -0500, Jeremy Linton wrote:
> Hi,
>
> On 5/23/20 1:44 PM, Russell King - ARM Linux admin wrote:
> > On Fri, May 22, 2020 at 04:30:55PM -0500, Jeremy Linton wrote:
> > > MMD's in the device list sometimes return 0 for their id.
> > > When that happens lets reset the id back to 0xfffffff so
> > > that we don't get a stub device created for it.
> > >
> > > This is a questionable commit, but i'm tossing it out
> > > there along with the comment that reading the spec
> > > seems to indicate that maybe there are further registers
> > > that could be probed in an attempt to resolve some futher
> > > "bad" phys. It sort of comes down to do we want unused phy
> > > devices floating around (potentially unmatched in dt) or
> > > do we want to cut them off early and let DT create them
> > > directly.
> >
> > I'm not sure what you mean "stub device" or "unused phy devices
> > floating around" - the individual MMDs are not treated as separate
> > "phy devices", but as one PHY device as a whole.
> >
>
> Well, I guess its clearer to say phy/mmd devices with a phy_id=0. Which is a
> problem if we don't have DT overriding the phy_id for a given address.
> Although AFAIK given a couple of the /sys/bus/mdio_bus/devices lists I've
> seen, and after studying this code for a while now, I think "bogus" phy's
> might be getting created*. I was far to easy, to upset the cart when I was
> hacking on this set, and end up with a directory chuck full of phys.
>
> So this gets close to one of the questions I asked in the cover letter. This
> patch and 09/11 serve to cut off possibly valid phy's which are failing to
> identify themselves using the standard registers. Which per the 802.3 spec
> there is a blurb about 0 in the id registers for some cases. Its not really
> a critical problem for ACPI machines to have these phys around (OTOH, there
> might be issues with c22 phys on c45 electrical buses that respond to c45
> reg requests but don't set the c22 regs flag, I haven't seen that yet.).
If you have a classical clause 22 PHY on a clause 45 bus, it isn't
going to respond to clause 45 cycles, so it isn't going to respond to
a request to read the devices-in-package register, so there is no
"c22 regs" flag.
> I
> considered dropping this patch, and 9/11 was a last minute addition. I kept
> it because I was worried all those extra "reserved" MMDs would end up with
> id = 0's in there and break something.
>
> * In places where there isn't actually a phy, likely a large part of the
> problem was clearing the c22 bit, which allowed 0xFFFFFFFF returns to slip
> through the devices list.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTC for 0.8m (est. 1762m) line in suburbia: sync at 13.1Mbps down 424kbps up
next prev parent reply other threads:[~2020-05-25 8:20 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 [this message]
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
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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