netdev - Re: [PATCH v2 net-next 05/10] phy: add phy_get_rx_polarity() and phy_get_tx

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Message-ID: <20260110180433.bfg2hxbdjkfllkiq@skbuf>
Date: Sat, 10 Jan 2026 20:04:33 +0200
From: Vladimir Oltean <vladimir.oltean@....com>
To: Bjørn Mork <bjorn@...k.no>
Cc: netdev@...r.kernel.org, devicetree@...r.kernel.org,
	linux-phy@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-mediatek@...ts.infradead.org,
	Daniel Golle <daniel@...rotopia.org>,
	Horatiu Vultur <horatiu.vultur@...rochip.com>,
	Andrew Lunn <andrew@...n.ch>,
	Heiner Kallweit <hkallweit1@...il.com>,
	Russell King <linux@...linux.org.uk>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, Vinod Koul <vkoul@...nel.org>,
	Neil Armstrong <neil.armstrong@...aro.org>,
	Matthias Brugger <matthias.bgg@...il.com>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	Eric Woudstra <ericwouds@...il.com>,
	Marek Behún <kabel@...nel.org>,
	Lee Jones <lee@...nel.org>,
	Patrice Chotard <patrice.chotard@...s.st.com>
Subject: Re: [PATCH v2 net-next 05/10] phy: add phy_get_rx_polarity() and
 phy_get_tx_polarity()

Hi Bjørn,

On Wed, Jan 07, 2026 at 09:12:28AM +0100, Bjørn Mork wrote:
> Vladimir Oltean <vladimir.oltean@....com> writes:
> 
> > +static int fwnode_get_u32_prop_for_name(struct fwnode_handle *fwnode,
> > +					const char *name,
> > +					const char *props_title,
> > +					const char *names_title,
> > +					unsigned int default_val,
> > +					unsigned int *val)
> > +{
> > +	int err, n_props, n_names, idx = -1;
> > +	u32 *props;
> > +
> > +	if (!name) {
> > +		pr_err("Lookup key inside \"%s\" is mandatory\n", names_title);
> > +		return -EINVAL;
> > +	}
> > +
> > +	if (!fwnode) {
> > +		*val = default_val;
> > +		return 0;
> > +	}
> > +
> > +	err = fwnode_property_count_u32(fwnode, props_title);
> > +	if (err < 0)
> > +		return err;
> > +	if (err == 0) {
> > +		*val = default_val;
> > +		return 0;
> > +	}
> > +	n_props = err;
> 
> I tried using this in the air_en8811h driver and started wondering if I
> have misunderstood something.
> 
> The problem I have is that fwnode_property_count_u32() returns -EINVAL
> if props_title is missing.  So if you have a node with the legacy
> "airoha,pnswap-rx" property instead of "rx-polarity", or more common: no
> polariy property at all, then we see -EINVAL returned from
> phy_get_rx_polarity().  Which is propagated back to config_init() and
> the phy fails to attach.  That can't be the intention?
> 
> The behaviour I expected is described by this test:
> 
> 
> /* Test: tx-polarity property is missing */
> static void phy_test_tx_polarity_is_missing(struct kunit *test)
> {
> 	static const struct property_entry entries[] = {
> 		{}
> 	};
> 	struct fwnode_handle *node;
> 	unsigned int val;
> 	int ret;
> 
> 	node = fwnode_create_software_node(entries, NULL);
> 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, node);
> 
> 	ret = phy_get_manual_tx_polarity(node, "sgmi", &val);
> 	KUNIT_EXPECT_EQ(test, ret, 0);
> 	KUNIT_EXPECT_EQ(test, val, PHY_POL_NORMAL);
> 
> 	fwnode_remove_software_node(node);
> }

Thanks for debugging and for the test! This is a regression from v1,
where I just checked the fwnode_property_count_u32() return code for
being <= 0.

I've integrated your test and added one more for RX. Do you have any
further comments, or shall I send an updated v3?