From: Jeremy Linton <jeremy.linton@arm.com>
To: Russell King - ARM Linux admin <linux@armlinux.org.uk>
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 01/11] net: phy: Don't report success if devices weren't found
Date: Sun, 24 May 2020 21:46:55 -0500 [thread overview]
Message-ID: <e6e08ca4-5a6d-5ea3-0f97-946f1d403568@arm.com> (raw)
In-Reply-To: <20200523182054.GW1551@shell.armlinux.org.uk>
Hi,
Thanks for taking a look at this.
On 5/23/20 1:20 PM, Russell King - ARM Linux admin wrote:
> On Fri, May 22, 2020 at 04:30:49PM -0500, Jeremy Linton wrote:
>> C45 devices are to return 0 for registers they haven't
>> implemented. This means in theory we can terminate the
>> device search loop without finding any MMDs. In that
>> case we want to immediately return indicating that
>> nothing was found rather than continuing to probe
>> and falling into the success state at the bottom.
>
> This is a little confusing when you read this comment:
>
> /* If mostly Fs, there is no device there,
> * then let's continue to probe more, as some
> * 10G PHYs have zero Devices In package,
> * e.g. Cortina CS4315/CS4340 PHY.
> */
>
> Since it appears to be talking about the case of a PHY where *devs will
> be zero. However, tracking down the original submission, it seems this
> is not the case at all, and the comment is grossly misleading.
>
> It seems these PHYs only report a valid data in the Devices In Package
> registers for devad=0 - it has nothing to do with a zero Devices In
> Package.
Yes, this ended up being my understanding of this commit, and is part of
my justification for starting the devices search at the reserved address
0 rather than 1.
>
> Can I suggest that this comment is fixed while we're changing the code
> to explicitly reject this "zero Devices In package" so that it's not
> confusing?
Its probably better to kill it in 5/11 with a mention that we are
starting at a reserved address?
OTOH, I'm a bit concerned that reading at 0 as the first address will
cause problems because the original code was only triggering it after a
read returning 0xFFFFFFFF at a valid MMD address. It does
simplify/clarify the loop though. If it weren't for this 0 read, I would
have tried to avoid some of the additional MMD reserved addresses.
next prev parent reply other threads:[~2020-05-25 2:46 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 [this message]
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
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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