On Fri, Mar 27, 2020 at 12:12:37PM +0000, Madalin Bucur (OSS) wrote:

quoted

-----Original Message-----
From: netdev-owner@vger.kernel.org <redacted> On
Behalf Of Russell King - ARM Linux admin
Sent: Friday, March 27, 2020 2:02 PM
To: Andrew Lunn <andrew@lunn.ch>
Cc: Florinel Iordache <redacted>; davem@davemloft.net;
netdev@vger.kernel.org; f.fainelli@gmail.com; hkallweit1@gmail.com;
devicetree@vger.kernel.org; linux-doc@vger.kernel.org; robh+dt@kernel.org;
mark.rutland@arm.com; kuba@kernel.org; corbet@lwn.net;
shawnguo@kernel.org; Leo Li [off-list ref]; Madalin Bucur (OSS)
[off-list ref]; Ioana Ciornei [off-list ref]; linux-
kernel@vger.kernel.org
Subject: Re: [PATCH net-next 3/9] net: phy: add kr phy connection type

On Fri, Mar 27, 2020 at 01:15:15AM +0100, Andrew Lunn wrote:

quoted

On Thu, Mar 26, 2020 at 03:51:16PM +0200, Florinel Iordache wrote:

quoted

Add support for backplane kr phy connection types currently available
(10gbase-kr, 40gbase-kr4) and the required phylink updates (cover all
the cases for KR modes which are clause 45 compatible to correctly

assign

quoted

quoted

phy_interface and phylink#supported)

Signed-off-by: Florinel Iordache <redacted>
---
 drivers/net/phy/phylink.c | 15 ++++++++++++---
 include/linux/phy.h       |  6 +++++-
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index fed0c59..db1bb87 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c

@@ -4,6 +4,7 @@
  * technologies such as SFP cages where the PHY is hot-pluggable.
  *
  * Copyright (C) 2015 Russell King
+ * Copyright 2020 NXP
  */
 #include <linux/ethtool.h>
 #include <linux/export.h>

@@ -303,7 +304,6 @@ static int phylink_parse_mode(struct phylink *pl,

struct fwnode_handle *fwnode)

quoted

quoted

 			break;

 		case PHY_INTERFACE_MODE_USXGMII:
-		case PHY_INTERFACE_MODE_10GKR:

We might have a backwards compatibility issue here. If i remember
correctly, there are some boards out in the wild using
PHY_INTERFACE_MODE_10GKR not PHY_INTERFACE_MODE_10GBASER.

See e0f909bc3a242296da9ccff78277f26d4883a79d

Russell, what do you say about this?

Yes, and that's a point that I made when I introduced 10GBASER to
correct that mistake.  It is way too soon to change this; it will
definitely cause regressions:

$ grep 10gbase-kr arch/*/boot/dts -r
arch/arm64/boot/dts/marvell/cn9131-db.dts:      phy-mode = "10gbase-kr";
arch/arm64/boot/dts/marvell/armada-8040-mcbin.dts:      phy-mode =
"10gbase-kr";
arch/arm64/boot/dts/marvell/armada-8040-mcbin.dts:      phy-mode =
"10gbase-kr";
arch/arm64/boot/dts/marvell/armada-7040-db.dts:    phy-mode = "10gbase-
kr";
arch/arm64/boot/dts/marvell/armada-8040-mcbin-singleshot.dts:   phy-mode =
"10gbase-kr";
arch/arm64/boot/dts/marvell/armada-8040-mcbin-singleshot.dts:   phy-mode =
"10gbase-kr";
arch/arm64/boot/dts/marvell/armada-8040-clearfog-gt-8k.dts:     phy-mode =
"10gbase-kr";
arch/arm64/boot/dts/marvell/armada-8040-db.dts: phy-mode = "10gbase-kr";
arch/arm64/boot/dts/marvell/armada-8040-db.dts: phy-mode = "10gbase-kr";
arch/arm64/boot/dts/marvell/cn9132-db.dts:      phy-mode = "10gbase-kr";
arch/arm64/boot/dts/marvell/cn9130-db.dts:      phy-mode = "10gbase-kr";

So any change to the existing PHY_INTERFACE_MODE_10GKR will likely
break all these platforms.

Hi Russell,

I hoped a fix for those would be in by now, it's not useful to leave them like
that.

I haven't had the time to address the ones I know about, sorry.
However, there are some platforms in that list which I've no
knowledge of, which I therefore can't change.

We have a similar situation, where all boards using XFI interfaces contain
phy-connection-type="xgmii" for a long time now but that did not stop anyone from
adding a warning in the Aquantia driver:

+       WARN(phydev->interface == PHY_INTERFACE_MODE_XGMII,
+            "Your devicetree is out of date, please update it. The AQR107 family doesn't support XGMII, maybe you mean USXGMII.\n");
+

Maybe we need a warning added here too, until the proper phy-mode is used for
these boards, to allow for a transition period.

Adding a warning can only be done once the current users have been
updated, otherwise it's technically introducing a regression.  Plus
some users may actually be correct.  I never did get to the bottom
of that, because that required discussion and no one seems willing
to discuss it.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 10.2Mbps down 587kbps up