Date:   Sat, 6 Aug 2022 21:58:16 +0200
From:   Christian Marangi <ansuelsmth@...il.com>
To:     Vladimir Oltean <vladimir.oltean@....com>
Cc:     netdev@...r.kernel.org, devicetree@...r.kernel.org,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Oleksij Rempel <linux@...pel-privat.de>,
        John Crispin <john@...ozen.org>,
        Kurt Kanzenbach <kurt@...utronix.de>,
        Mans Rullgard <mans@...sr.com>,
        Arun Ramadoss <arun.ramadoss@...rochip.com>,
        Woojung Huh <woojung.huh@...rochip.com>,
        UNGLinuxDriver@...rochip.com,
        Claudiu Manoil <claudiu.manoil@....com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        George McCollister <george.mccollister@...il.com>,
        DENG Qingfang <dqfext@...il.com>,
        Sean Wang <sean.wang@...iatek.com>,
        Landen Chao <Landen.Chao@...iatek.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Hauke Mehrtens <hauke@...ke-m.de>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        Aleksander Jan Bajkowski <olek2@...pl>,
        Alvin Šipraga <alsi@...g-olufsen.dk>,
        Luiz Angelo Daros de Luca <luizluca@...il.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Pawel Dembicki <paweldembicki@...il.com>,
        Clément Léger <clement.leger@...tlin.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Russell King <rmk+kernel@...linux.org.uk>,
        Marek Behún <kabel@...nel.org>,
        Marcin Wojtas <mw@...ihalf.com>, Marek Vasut <marex@...x.de>,
        linux-renesas-soc@...r.kernel.org,
        Frank Rowand <frowand.list@...il.com>
Subject: Re: [RFC PATCH v3 net-next 10/10] net: dsa: make phylink-related OF
 properties mandatory on DSA and CPU ports

On Sat, Aug 06, 2022 at 05:10:59PM +0300, Vladimir Oltean wrote:
> Early DSA drivers were kind of simplistic in that they assumed a fairly
> narrow hardware layout. User ports would have integrated PHYs at an
> internal MDIO address that is derivable from the port number, and shared
> (DSA and CPU) ports would have an MII-style (serial or parallel)
> connection to another MAC. Phylib and then phylink were used to drive
> the internal PHYs, and this needed little to no description through the
> platform data structures. Bringing up the shared ports at the maximum
> supported link speed was the responsibility of the drivers.
> 
> As a result of this, when these early drivers were converted from
> platform data to the new DSA OF bindings, there was no link information
> translated into the first DT bindings.
> 
> https://lore.kernel.org/all/YtXFtTsf++AeDm1l@lunn.ch/
> 
> Later, phylink was adopted for shared ports as well, and today we have a
> workaround in place, introduced by commit a20f997010c4 ("net: dsa: Don't
> instantiate phylink for CPU/DSA ports unless needed"). There, DSA checks
> for the presence of phy-handle/fixed-link/managed OF properties, and if
> missing, phylink registration would be skipped. This is because phylink
> is optional for some drivers (the shared ports already work without it),
> but the process of starting to register a port with phylink is
> irreversible: if phylink_create() fails to find the fwnode properties it
> needs, it bails out and it leaves the ports inoperational (because
> phylink expects ports to be initially down, so DSA necessarily takes
> them down, and doesn't know how to put them back up again).
> 
> DSA being a common framework, new drivers opt into this workaround
> willy-nilly, but the ideal behavior from the DSA core's side would have
> been to not interfere with phylink's process of failing at all. This
> isn't possible because of regression concerns with pre-phylink DT blobs,
> but at least DSA should put a stop to the proliferation of more of such
> cases that rely on the workaround to skip phylink registration, and
> sanitize the environment that new drivers work in.
> 
> To that end, create a list of compatible strings for which the
> workaround is preserved, and don't apply the workaround for any drivers
> outside that list (this includes new drivers).
> 
> In some cases, we make the assumption that even existing drivers don't
> rely on DSA's workaround, and we do this by looking at the device trees
> in which they appear. We can't fully know what is the situation with
> downstream DT blobs, but we can guess the overall trend by studying the
> DT blobs that were submitted upstream. If there are upstream blobs that
> have lacking descriptions, we take it as very likely that there are many
> more downstream blobs that do so too. If all upstream blobs have
> complete descriptions, we take that as a hint that the driver is a
> candidate for strict validation (considering that most bindings are
> copy-pasted). If there are no upstream DT blobs, we take the
> conservative route of skipping validation, unless the driver maintainer
> instructs us otherwise.
> 
> The driver situation is as follows:
> 
> ar9331
> ~~~~~~
> 
>     compatible strings:
>     - qca,ar9331-switch
> 
>     1 occurrence in mainline device trees, part of SoC dtsi
>     (arch/mips/boot/dts/qca/ar9331.dtsi), description is not problematic.
> 
>     Verdict: opt into validation.
> 
> b53
> ~~~
> 
>     compatible strings:
>     - brcm,bcm5325
>     - brcm,bcm53115
>     - brcm,bcm53125
>     - brcm,bcm53128
>     - brcm,bcm5365
>     - brcm,bcm5389
>     - brcm,bcm5395
>     - brcm,bcm5397
>     - brcm,bcm5398
> 
>     - brcm,bcm53010-srab
>     - brcm,bcm53011-srab
>     - brcm,bcm53012-srab
>     - brcm,bcm53018-srab
>     - brcm,bcm53019-srab
>     - brcm,bcm5301x-srab
>     - brcm,bcm11360-srab
>     - brcm,bcm58522-srab
>     - brcm,bcm58525-srab
>     - brcm,bcm58535-srab
>     - brcm,bcm58622-srab
>     - brcm,bcm58623-srab
>     - brcm,bcm58625-srab
>     - brcm,bcm88312-srab
>     - brcm,cygnus-srab
>     - brcm,nsp-srab
>     - brcm,omega-srab
> 
>     - brcm,bcm3384-switch
>     - brcm,bcm6328-switch
>     - brcm,bcm6368-switch
>     - brcm,bcm63xx-switch
> 
>     I've found at least these mainline DT blobs with problems:
> 
>     arch/arm/boot/dts/bcm47094-linksys-panamera.dts
>     - lacks phy-mode
>     arch/arm/boot/dts/bcm47189-tenda-ac9.dts
>     - lacks phy-mode and fixed-link
>     arch/arm/boot/dts/bcm47081-luxul-xap-1410.dts
>     arch/arm/boot/dts/bcm47081-luxul-xwr-1200.dts
>     arch/arm/boot/dts/bcm47081-buffalo-wzr-600dhp2.dts
>     - lacks phy-mode and fixed-link
>     arch/arm/boot/dts/bcm47094-luxul-xbr-4500.dts
>     arch/arm/boot/dts/bcm4708-smartrg-sr400ac.dts
>     arch/arm/boot/dts/bcm4708-luxul-xap-1510.dts
>     arch/arm/boot/dts/bcm953012er.dts
>     arch/arm/boot/dts/bcm4708-netgear-r6250.dts
>     arch/arm/boot/dts/bcm4708-buffalo-wzr-1166dhp-common.dtsi
>     arch/arm/boot/dts/bcm4708-luxul-xwc-1000.dts
>     arch/arm/boot/dts/bcm47094-luxul-abr-4500.dts
>     - lacks phy-mode and fixed-link
>     arch/arm/boot/dts/bcm53016-meraki-mr32.dts
>     - lacks phy-mode
> 
>     Verdict: opt all switches out of strict validation.
> 
> bcm_sf2
> ~~~~~~~
> 
>     compatible strings:
>     - brcm,bcm4908-switch
>     - brcm,bcm7445-switch-v4.0
>     - brcm,bcm7278-switch-v4.0
>     - brcm,bcm7278-switch-v4.8
> 
>     A single occurrence in mainline
>     (arch/arm64/boot/dts/broadcom/bcm4908/bcm4908.dtsi), part of a SoC
>     dtsi, valid description. Florian Fainelli explains that most of the
>     bcm_sf2 device trees lack a full description for the internal IMP
>     ports.
> 
>     Verdict: opt the BCM4908 into strict validation, and opt out the
>     rest. Note that even though BCM4908 has strict DT bindings, it still
>     does not register with phylink on the IMP port due to it implementing
>     ->adjust_link().
> 
> hellcreek
> ~~~~~~~~~
> 
>     compatible strings:
>     - hirschmann,hellcreek-de1soc-r1
> 
>     No occurrence in mainline device trees. Kurt Kanzenbach confirms
>     that the downstream device tree lacks phy-mode and fixed link, and
>     needs work.
> 
>     Verdict: opt out of validation.
> 
> lan9303
> ~~~~~~~
> 
>     compatible strings:
>     - smsc,lan9303-mdio
>     - smsc,lan9303-i2c
> 
>     1 occurrence in mainline device trees:
>     arch/arm/boot/dts/imx53-kp-hsc.dts
>     - no phy-mode, no fixed-link
> 
>     Verdict: opt out of validation.
> 
> lantiq_gswip
> ~~~~~~~~~~~~
> 
>     compatible strings:
>     - lantiq,xrx200-gswip
>     - lantiq,xrx300-gswip
>     - lantiq,xrx330-gswip
> 
>     No occurrences in mainline device trees. Martin Blumenstingl
>     confirms that the downstream OpenWrt device trees lack a proper
>     fixed-link and need work, and that the incomplete description can
>     even be seen in the example from
>     Documentation/devicetree/bindings/net/dsa/lantiq-gswip.txt.
> 
>     Verdict: opt out of validation.
> 
> microchip ksz
> ~~~~~~~~~~~~~
> 
>     compatible strings:
>     - microchip,ksz8765
>     - microchip,ksz8794
>     - microchip,ksz8795
>     - microchip,ksz8863
>     - microchip,ksz8873
>     - microchip,ksz9477
>     - microchip,ksz9897
>     - microchip,ksz9893
>     - microchip,ksz9563
>     - microchip,ksz8563
>     - microchip,ksz9567
>     - microchip,lan9370
>     - microchip,lan9371
>     - microchip,lan9372
>     - microchip,lan9373
>     - microchip,lan9374
> 
>     5 occurrences in mainline device trees, all descriptions are valid.
>     But we had a snafu for the ksz8795 and ksz9477 drivers where the
>     phy-mode property would be expected to be located directly under the
>     'switch' node rather than under a port OF node. It was fixed by
>     commit edecfa98f602 ("net: dsa: microchip: look for phy-mode in port
>     nodes"). The driver still has compatibility with the old DT blobs.
>     The lan937x support was added later than the above snafu was fixed,
>     and even though it has support for the broken DT blobs by virtue of
>     sharing a common probing function, I'll take it that its DT blobs
>     are correct.
> 
>     Verdict: opt lan937x into validation, and the others out.
> 
> mt7530
> ~~~~~~
> 
>     compatible strings
>     - mediatek,mt7621
>     - mediatek,mt7530
>     - mediatek,mt7531
> 
>     Multiple occurrences in mainline device trees, one is part of an SoC
>     dtsi (arch/mips/boot/dts/ralink/mt7621.dtsi), all descriptions are fine.
> 
>     Verdict: opt into strict validation.
> 
> mv88e6060
> ~~~~~~~~~
> 
>     compatible string:
>     - marvell,mv88e6060
> 
>     no occurrences in mainline, nobody knows anybody who uses it.
> 
>     Verdict: opt out of strict validation.
> 
> mv88e6xxx
> ~~~~~~~~~
> 
>     compatible strings:
>     - marvell,mv88e6085
>     - marvell,mv88e6190
>     - marvell,mv88e6250
> 
>     Device trees that have incomplete descriptions of CPU or DSA ports:
>     arch/arm64/boot/dts/freescale/imx8mq-zii-ultra.dtsi
>     - lacks phy-mode
>     arch/arm64/boot/dts/marvell/cn9130-crb.dtsi
>     - lacks phy-mode and fixed-link
>     arch/arm/boot/dts/vf610-zii-ssmb-spu3.dts
>     - lacks phy-mode
>     arch/arm/boot/dts/kirkwood-mv88f6281gtw-ge.dts
>     - lacks phy-mode
>     arch/arm/boot/dts/vf610-zii-spb4.dts
>     - lacks phy-mode
>     arch/arm/boot/dts/vf610-zii-cfu1.dts
>     - lacks phy-mode
>     arch/arm/boot/dts/vf610-zii-dev-rev-c.dts
>     - lacks phy-mode on CPU port, fixed-link on DSA ports
>     arch/arm/boot/dts/vf610-zii-dev-rev-b.dts
>     - lacks phy-mode on CPU port
>     arch/arm/boot/dts/armada-381-netgear-gs110emx.dts
>     - lacks phy-mode
>     arch/arm/boot/dts/vf610-zii-scu4-aib.dts
>     - lacks fixed-link on xgmii DSA ports and/or in-band-status on
>       2500base-x DSA ports, and phy-mode on CPU port
>     arch/arm/boot/dts/imx6qdl-gw5904.dtsi
>     - lacks phy-mode and fixed-link
>     arch/arm/boot/dts/armada-385-clearfog-gtr-l8.dts
>     - lacks phy-mode and fixed-link
>     arch/arm/boot/dts/vf610-zii-ssmb-dtu.dts
>     - lacks phy-mode
>     arch/arm/boot/dts/kirkwood-dir665.dts
>     - lacks phy-mode
>     arch/arm/boot/dts/kirkwood-rd88f6281.dtsi
>     - lacks phy-mode
>     arch/arm/boot/dts/orion5x-netgear-wnr854t.dts
>     - lacks phy-mode and fixed-link
>     arch/arm/boot/dts/armada-388-clearfog.dts
>     - lacks phy-mode
>     arch/arm/boot/dts/armada-xp-linksys-mamba.dts
>     - lacks phy-mode
>     arch/arm/boot/dts/armada-385-linksys.dtsi
>     - lacks phy-mode
>     arch/arm/boot/dts/imx6q-b450v3.dts
>     arch/arm/boot/dts/imx6q-b850v3.dts
>     - has a phy-handle but not a phy-mode?
>     arch/arm/boot/dts/armada-370-rd.dts
>     - lacks phy-mode
>     arch/arm/boot/dts/kirkwood-linksys-viper.dts
>     - lacks phy-mode
>     arch/arm/boot/dts/imx51-zii-rdu1.dts
>     - lacks phy-mode
>     arch/arm/boot/dts/imx51-zii-scu2-mezz.dts
>     - lacks phy-mode
>     arch/arm/boot/dts/imx6qdl-zii-rdu2.dtsi
>     - lacks phy-mode
>     arch/arm/boot/dts/armada-385-clearfog-gtr-s4.dts
>     - lacks phy-mode and fixed-link
> 
>     Verdict: opt out of validation.
> 
> ocelot
> ~~~~~~
> 
>     compatible strings:
>     - mscc,vsc9953-switch
>     - felix (arch/arm64/boot/dts/freescale/fsl-ls1028a.dtsi) is a PCI
>       device, has no compatible string
> 
>     2 occurrences in mainline, both are part of SoC dtsi and complete.
> 
>     Verdict: opt into strict validation.
> 
> qca8k
> ~~~~~
> 
>     compatible strings:
>     - qca,qca8327
>     - qca,qca8328
>     - qca,qca8334
>     - qca,qca8337
> 
>     5 occurrences in mainline device trees, none of the descriptions are
>     problematic.
> 
>     Verdict: opt into validation.

I notice some have strict validation and other simple validation. I
didn't understand from the commit description where strict is used
instead of simple one.

I'm asking this for qca8k as from what we notice with device that use
qca8k the master ports always needs to have info in dt as we reset the
switch and always need to correctly setup the port.

> 
> realtek
> ~~~~~~~
> 
>     compatible strings:
>     - realtek,rtl8366rb
>     - realtek,rtl8365mb
> 
>     2 occurrences in mainline, both descriptions are fine, additionally
>     rtl8365mb.c has a comment "The device tree firmware should also
>     specify the link partner of the extension port - either via a
>     fixed-link or other phy-handle."
> 
>     Verdict: opt into validation.
> 
> rzn1_a5psw
> ~~~~~~~~~~
> 
>     compatible strings:
>     - renesas,rzn1-a5psw
> 
>     One single occurrence, part of SoC dtsi
>     (arch/arm/boot/dts/r9a06g032.dtsi), description is fine.
> 
>     Verdict: opt into validation.
> 
> sja1105
> ~~~~~~~
> 
>     Driver already validates its port OF nodes in
>     sja1105_parse_ports_node().
> 
>     Verdict: opt into validation.
> 
> vsc73xx
> ~~~~~~~
> 
>     compatible strings:
>     - vitesse,vsc7385
>     - vitesse,vsc7388
>     - vitesse,vsc7395
>     - vitesse,vsc7398
> 
>     2 occurrences in mainline device trees, both descriptions are fine.
> 
>     Verdict: opt into validation.
> 
> xrs700x
> ~~~~~~~
> 
>     compatible strings:
>     - arrow,xrs7003e
>     - arrow,xrs7003f
>     - arrow,xrs7004e
>     - arrow,xrs7004f
> 
>     no occurrences in mainline, we don't know.
> 
>     Verdict: opt out of strict validation.
> 
> Because there is a pattern where newly added switches reuse existing
> drivers more often than introducing new ones, I've opted for deciding
> who gets to opt into the workaround based on an OF compatible match
> table in the DSA core. The alternative would have been to add another
> boolean property to struct dsa_switch, like configure_vlan_while_not_filtering.
> But this avoids situations where sometimes driver maintainers obfuscate
> what goes on by sharing a common probing function, and therefore making
> new switches inherit old quirks.
> 
> Side note, we also warn about missing properties for drivers that rely
> on the workaround. This isn't an indication that we'll break
> compatibility with those DT blobs any time soon, but is rather done to
> raise awareness about the change, for future DT blob authors.
> 
> Cc: Rob Herring <robh+dt@...nel.org>
> Cc: Frank Rowand <frowand.list@...il.com>
> Acked-by: Alvin Šipraga <alsi@...g-olufsen.dk> # realtek
> Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
> ---
> v1->v2: print warnings even for drivers skipping phylink registration,
>         move code placement
> v2->v3: reword commit message
> 
>  net/dsa/port.c | 175 +++++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 170 insertions(+), 5 deletions(-)
> 
> diff --git a/net/dsa/port.c b/net/dsa/port.c
> index 4b6139bff217..c07a7c69d5e0 100644
> --- a/net/dsa/port.c
> +++ b/net/dsa/port.c
> @@ -1650,22 +1650,187 @@ static int dsa_shared_port_phylink_register(struct dsa_port *dp)
>  	return err;
>  }
>  
> +/* During the initial DSA driver migration to OF, port nodes were sometimes
> + * added to device trees with no indication of how they should operate from a
> + * link management perspective (phy-handle, fixed-link, etc). Additionally, the
> + * phy-mode may be absent. The interpretation of these port OF nodes depends on
> + * their type.
> + *
> + * User ports with no phy-handle or fixed-link are expected to connect to an
> + * internal PHY located on the ds->slave_mii_bus at an MDIO address equal to
> + * the port number. This description is still actively supported.
> + *
> + * Shared (CPU and DSA) ports with no phy-handle or fixed-link are expected to
> + * operate at the maximum speed that their phy-mode is capable of. If the
> + * phy-mode is absent, they are expected to operate using the phy-mode
> + * supported by the port that gives the highest link speed. It is unspecified
> + * if the port should use flow control or not, half duplex or full duplex, or
> + * if the phy-mode is a SERDES link, whether in-band autoneg is expected to be
> + * enabled or not.
> + *
> + * In the latter case of shared ports, omitting the link management description
> + * from the firmware node is deprecated and strongly discouraged. DSA uses
> + * phylink, which rejects the firmware nodes of these ports for lacking
> + * required properties.
> + *
> + * For switches in this table, DSA will skip enforcing validation and will
> + * later omit registering a phylink instance for the shared ports, if they lack
> + * a fixed-link, a phy-handle, or a managed = "in-band-status" property.
> + * It becomes the responsibility of the driver to ensure that these ports
> + * operate at the maximum speed (whatever this means) and will interoperate
> + * with the DSA master or other cascade port, since phylink methods will not be
> + * invoked for them.
> + *
> + * If you are considering expanding this table for newly introduced switches,
> + * think again. It is OK to remove switches from this table if there aren't DT
> + * blobs in circulation which rely on defaulting the shared ports.
> + */
> +static const char * const dsa_switches_dont_enforce_validation[] = {
> +#if IS_ENABLED(CONFIG_NET_DSA_XRS700X)
> +	"arrow,xrs7003e",
> +	"arrow,xrs7003f",
> +	"arrow,xrs7004e",
> +	"arrow,xrs7004f",
> +#endif
> +#if IS_ENABLED(CONFIG_B53)
> +	"brcm,bcm5325",
> +	"brcm,bcm53115",
> +	"brcm,bcm53125",
> +	"brcm,bcm53128",
> +	"brcm,bcm5365",
> +	"brcm,bcm5389",
> +	"brcm,bcm5395",
> +	"brcm,bcm5397",
> +	"brcm,bcm5398",
> +	"brcm,bcm53010-srab",
> +	"brcm,bcm53011-srab",
> +	"brcm,bcm53012-srab",
> +	"brcm,bcm53018-srab",
> +	"brcm,bcm53019-srab",
> +	"brcm,bcm5301x-srab",
> +	"brcm,bcm11360-srab",
> +	"brcm,bcm58522-srab",
> +	"brcm,bcm58525-srab",
> +	"brcm,bcm58535-srab",
> +	"brcm,bcm58622-srab",
> +	"brcm,bcm58623-srab",
> +	"brcm,bcm58625-srab",
> +	"brcm,bcm88312-srab",
> +	"brcm,cygnus-srab",
> +	"brcm,nsp-srab",
> +	"brcm,omega-srab",
> +	"brcm,bcm3384-switch",
> +	"brcm,bcm6328-switch",
> +	"brcm,bcm6368-switch",
> +	"brcm,bcm63xx-switch",
> +#endif
> +#if IS_ENABLED(CONFIG_NET_DSA_BCM_SF2)
> +	"brcm,bcm7445-switch-v4.0",
> +	"brcm,bcm7278-switch-v4.0",
> +	"brcm,bcm7278-switch-v4.8",
> +#endif
> +#if IS_ENABLED(CONFIG_NET_DSA_HIRSCHMANN_HELLCREEK)
> +	"hirschmann,hellcreek-de1soc-r1",
> +#endif
> +#if IS_ENABLED(CONFIG_NET_DSA_LANTIQ_GSWIP)
> +	"lantiq,xrx200-gswip",
> +	"lantiq,xrx300-gswip",
> +	"lantiq,xrx330-gswip",
> +#endif
> +#if IS_ENABLED(CONFIG_NET_DSA_MV88E6060)
> +	"marvell,mv88e6060",
> +#endif
> +#if IS_ENABLED(CONFIG_NET_DSA_MV88E6XXX)
> +	"marvell,mv88e6085",
> +	"marvell,mv88e6190",
> +	"marvell,mv88e6250",
> +#endif
> +#if IS_ENABLED(CONFIG_NET_DSA_MICROCHIP_KSZ_COMMON)
> +	"microchip,ksz8765",
> +	"microchip,ksz8794",
> +	"microchip,ksz8795",
> +	"microchip,ksz8863",
> +	"microchip,ksz8873",
> +	"microchip,ksz9477",
> +	"microchip,ksz9897",
> +	"microchip,ksz9893",
> +	"microchip,ksz9563",
> +	"microchip,ksz8563",
> +	"microchip,ksz9567",
> +#endif
> +#if IS_ENABLED(CONFIG_NET_DSA_SMSC_LAN9303_MDIO)
> +	"smsc,lan9303-mdio",
> +#endif
> +#if IS_ENABLED(CONFIG_NET_DSA_SMSC_LAN9303_I2C)
> +	"smsc,lan9303-i2c",
> +#endif
> +	NULL,
> +};
> +
> +static void dsa_shared_port_validate_of(struct dsa_port *dp,
> +					bool *missing_phy_mode,
> +					bool *missing_link_description)
> +{
> +	struct device_node *dn = dp->dn, *phy_np;
> +	struct dsa_switch *ds = dp->ds;
> +	phy_interface_t mode;
> +
> +	*missing_phy_mode = false;
> +	*missing_link_description = false;
> +
> +	if (of_get_phy_mode(dn, &mode)) {
> +		*missing_phy_mode = true;
> +		dev_err(ds->dev,
> +			"OF node %pOF of %s port %d lacks the required \"phy-mode\" property\n",
> +			dn, dsa_port_is_cpu(dp) ? "CPU" : "DSA", dp->index);
> +	}
> +
> +	/* Note: of_phy_is_fixed_link() also returns true for
> +	 * managed = "in-band-status"
> +	 */
> +	if (of_phy_is_fixed_link(dn))
> +		return;
> +
> +	phy_np = of_parse_phandle(dn, "phy-handle", 0);
> +	if (phy_np) {
> +		of_node_put(phy_np);
> +		return;
> +	}
> +
> +	*missing_link_description = true;
> +
> +	dev_err(ds->dev,
> +		"OF node %pOF of %s port %d lacks the required \"phy-handle\", \"fixed-link\" or \"managed\" properties\n",
> +		dn, dsa_port_is_cpu(dp) ? "CPU" : "DSA", dp->index);
> +}
> +
>  int dsa_shared_port_link_register_of(struct dsa_port *dp)
>  {
>  	struct dsa_switch *ds = dp->ds;
> -	struct device_node *phy_np;
> +	bool missing_link_description;
> +	bool missing_phy_mode;
>  	int port = dp->index;
>  
> +	dsa_shared_port_validate_of(dp, &missing_phy_mode,
> +				    &missing_link_description);
> +
> +	if ((missing_phy_mode || missing_link_description) &&
> +	    !of_device_compatible_match(ds->dev->of_node,
> +					dsa_switches_dont_enforce_validation))
> +		return -EINVAL;
> +
>  	if (!ds->ops->adjust_link) {
> -		phy_np = of_parse_phandle(dp->dn, "phy-handle", 0);
> -		if (of_phy_is_fixed_link(dp->dn) || phy_np) {
> +		if (missing_link_description) {
> +			dev_warn(ds->dev,
> +				 "Skipping phylink registration for %s port %d\n",
> +				 dsa_port_is_cpu(dp) ? "CPU" : "DSA", dp->index);
> +		} else {
>  			if (ds->ops->phylink_mac_link_down)
>  				ds->ops->phylink_mac_link_down(ds, port,
>  					MLO_AN_FIXED, PHY_INTERFACE_MODE_NA);
> -			of_node_put(phy_np);
> +
>  			return dsa_shared_port_phylink_register(dp);
>  		}
> -		of_node_put(phy_np);
>  		return 0;
>  	}
>  
> -- 
> 2.34.1
> 

-- 
	Ansuel

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