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Mon, 09 Mar 2026 02:18:59 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-gpio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: multipart/signed; boundary=840703edd9f3f1e1e79a02bb78a8d4f69f696b0531524c2c45c8075436e0; micalg=pgp-sha512; protocol="application/pgp-signature" Date: Mon, 09 Mar 2026 10:18:50 +0100 Message-Id: Cc: "Vinod Koul" , "Neil Armstrong" , , , , , , , , , , , , , , , , , , , , , "Andrzej Hajda" , "Robert Foss" , "Laurent Pinchart" , "Jonas Karlman" , "Jernej Skrabec" , "Maarten Lankhorst" , "Maxime Ripard" , "Thomas Zimmermann" , "David Airlie" , "Simona Vetter" , "Andy Yan" , "Marc Kleine-Budde" , "Vincent Mailhol" , "Nicolas Ferre" , "Alexandre Belloni" , "Claudiu Beznea" , "Markus Schneider-Pargmann" , "Geert Uytterhoeven" , "Magnus Damm" Subject: Re: [PATCH v2 phy-next 14/24] phy: introduce phy_get_max_link_rate() helper for consumers From: "Markus Schneider-Pargmann" To: , X-Mailer: aerc 0.21.0 References: <20260308114009.2546587-1-vladimir.oltean@nxp.com> <20260308114009.2546587-15-vladimir.oltean@nxp.com> In-Reply-To: <20260308114009.2546587-15-vladimir.oltean@nxp.com> --840703edd9f3f1e1e79a02bb78a8d4f69f696b0531524c2c45c8075436e0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Hi, On Sun Mar 8, 2026 at 12:39 PM CET, vladimir.oltean wrote: > Consumer drivers shouldn't dereference struct phy, not even to get to > its attributes. > > We have phy_get_bus_width() as a precedent for getting the bus_width > attribute, so let's add phy_get_max_link_rate() and use it in DRM and > CAN drivers. > > In CAN drivers, the transceiver is acquired through devm_phy_optional_get= () > and NULL is given by the API as a non-error case, so the PHY API should > also tolerate NULL coming back to it. This means we can further simplify > the call sites that test for the NULL quality of the transceiver. Thanks for adding this. > > Signed-off-by: Vladimir Oltean > --- > Cc: Andrzej Hajda > Cc: Neil Armstrong > Cc: Robert Foss > Cc: Laurent Pinchart > Cc: Jonas Karlman > Cc: Jernej Skrabec > Cc: Maarten Lankhorst > Cc: Maxime Ripard > Cc: Thomas Zimmermann > Cc: David Airlie > Cc: Simona Vetter > Cc: Andy Yan > Cc: Marc Kleine-Budde > Cc: Vincent Mailhol > Cc: Nicolas Ferre > Cc: Alexandre Belloni > Cc: Claudiu Beznea > Cc: Markus Schneider-Pargmann > Cc: Geert Uytterhoeven > Cc: Magnus Damm > > v1->v2: make phy_get_bus_width() NULL-tolerant to simplify CAN callers > --- > drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c | 4 ++-- > drivers/gpu/drm/bridge/synopsys/dw-dp.c | 2 +- > drivers/net/can/at91_can.c | 3 +-- > drivers/net/can/flexcan/flexcan-core.c | 3 +-- > drivers/net/can/m_can/m_can_platform.c | 3 +-- For m_can: Acked-by: Markus Schneider-Pargmann Best Markus > drivers/net/can/rcar/rcar_canfd.c | 3 +-- > drivers/phy/phy-core.c | 9 +++++++++ > include/linux/phy/phy.h | 6 ++++++ > 8 files changed, 22 insertions(+), 11 deletions(-) > > diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/driver= s/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c > index a8b6ae58cb0a..ed7ed82ddb64 100644 > --- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c > +++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c > @@ -1300,7 +1300,7 @@ static u32 cdns_mhdp_get_training_interval_us(struc= t cdns_mhdp_device *mhdp, > =20 > static void cdns_mhdp_fill_host_caps(struct cdns_mhdp_device *mhdp) > { > - unsigned int link_rate; > + u32 link_rate; > =20 > /* Get source capabilities based on PHY attributes */ > =20 > @@ -1308,7 +1308,7 @@ static void cdns_mhdp_fill_host_caps(struct cdns_mh= dp_device *mhdp) > if (!mhdp->host.lanes_cnt) > mhdp->host.lanes_cnt =3D 4; > =20 > - link_rate =3D mhdp->phy->attrs.max_link_rate; > + link_rate =3D phy_get_max_link_rate(mhdp->phy); > if (!link_rate) > link_rate =3D drm_dp_bw_code_to_link_rate(DP_LINK_BW_8_1); > else > diff --git a/drivers/gpu/drm/bridge/synopsys/dw-dp.c b/drivers/gpu/drm/br= idge/synopsys/dw-dp.c > index 4ab6922dd79c..79c72ee8e263 100644 > --- a/drivers/gpu/drm/bridge/synopsys/dw-dp.c > +++ b/drivers/gpu/drm/bridge/synopsys/dw-dp.c > @@ -536,7 +536,7 @@ static int dw_dp_link_parse(struct dw_dp *dp, struct = drm_connector *connector) > =20 > link->revision =3D link->dpcd[DP_DPCD_REV]; > link->rate =3D min_t(u32, min(dp->plat_data.max_link_rate, > - dp->phy->attrs.max_link_rate * 100), > + phy_get_max_link_rate(dp->phy) * 100), > drm_dp_max_link_rate(link->dpcd)); > link->lanes =3D min_t(u8, phy_get_bus_width(dp->phy), > drm_dp_max_lane_count(link->dpcd)); > diff --git a/drivers/net/can/at91_can.c b/drivers/net/can/at91_can.c > index 58da323f14d7..7749da0a58f6 100644 > --- a/drivers/net/can/at91_can.c > +++ b/drivers/net/can/at91_can.c > @@ -1125,8 +1125,7 @@ static int at91_can_probe(struct platform_device *p= dev) > =20 > can_rx_offload_add_timestamp(dev, &priv->offload); > =20 > - if (transceiver) > - priv->can.bitrate_max =3D transceiver->attrs.max_link_rate; > + priv->can.bitrate_max =3D phy_get_max_link_rate(transceiver); > =20 > if (at91_is_sam9263(priv)) > dev->sysfs_groups[0] =3D &at91_sysfs_attr_group; > diff --git a/drivers/net/can/flexcan/flexcan-core.c b/drivers/net/can/fle= xcan/flexcan-core.c > index f5d22c61503f..093e48b8da58 100644 > --- a/drivers/net/can/flexcan/flexcan-core.c > +++ b/drivers/net/can/flexcan/flexcan-core.c > @@ -2210,8 +2210,7 @@ static int flexcan_probe(struct platform_device *pd= ev) > priv->reg_xceiver =3D reg_xceiver; > priv->transceiver =3D transceiver; > =20 > - if (transceiver) > - priv->can.bitrate_max =3D transceiver->attrs.max_link_rate; > + priv->can.bitrate_max =3D phy_get_max_link_rate(transceiver); > =20 > if (priv->devtype_data.quirks & FLEXCAN_QUIRK_NR_IRQ_3) { > priv->irq_boff =3D platform_get_irq(pdev, 1); > diff --git a/drivers/net/can/m_can/m_can_platform.c b/drivers/net/can/m_c= an/m_can_platform.c > index 56da411878af..2a0f163a683a 100644 > --- a/drivers/net/can/m_can/m_can_platform.c > +++ b/drivers/net/can/m_can/m_can_platform.c > @@ -131,8 +131,7 @@ static int m_can_plat_probe(struct platform_device *p= dev) > goto probe_fail; > } > =20 > - if (transceiver) > - mcan_class->can.bitrate_max =3D transceiver->attrs.max_link_rate; > + mcan_class->can.bitrate_max =3D phy_get_max_link_rate(transceiver); > =20 > priv->base =3D addr; > priv->mram_base =3D mram_addr; > diff --git a/drivers/net/can/rcar/rcar_canfd.c b/drivers/net/can/rcar/rca= r_canfd.c > index eaf8cac78038..9062db48d477 100644 > --- a/drivers/net/can/rcar/rcar_canfd.c > +++ b/drivers/net/can/rcar/rcar_canfd.c > @@ -1884,8 +1884,7 @@ static int rcar_canfd_channel_probe(struct rcar_can= fd_global *gpriv, u32 ch, > priv->transceiver =3D transceiver; > priv->channel =3D ch; > priv->gpriv =3D gpriv; > - if (transceiver) > - priv->can.bitrate_max =3D transceiver->attrs.max_link_rate; > + priv->can.bitrate_max =3D phy_get_max_link_rate(transceiver); > priv->can.clock.freq =3D fcan_freq; > dev_info(dev, "can_clk rate is %u\n", priv->can.clock.freq); > =20 > diff --git a/drivers/phy/phy-core.c b/drivers/phy/phy-core.c > index 0d0be494cfd7..737a760d97d1 100644 > --- a/drivers/phy/phy-core.c > +++ b/drivers/phy/phy-core.c > @@ -647,6 +647,15 @@ void phy_set_bus_width(struct phy *phy, int bus_widt= h) > } > EXPORT_SYMBOL_GPL(phy_set_bus_width); > =20 > +u32 phy_get_max_link_rate(struct phy *phy) > +{ > + if (!phy) > + return 0; > + > + return phy->attrs.max_link_rate; > +} > +EXPORT_SYMBOL_GPL(phy_get_max_link_rate); > + > /** > * _of_phy_get() - lookup and obtain a reference to a phy by phandle > * @np: device_node for which to get the phy > diff --git a/include/linux/phy/phy.h b/include/linux/phy/phy.h > index a7e2432ca1ae..34b656084caf 100644 > --- a/include/linux/phy/phy.h > +++ b/include/linux/phy/phy.h > @@ -57,6 +57,7 @@ int phy_notify_disconnect(struct phy *phy, int port); > int phy_notify_state(struct phy *phy, union phy_notify state); > int phy_get_bus_width(struct phy *phy); > void phy_set_bus_width(struct phy *phy, int bus_width); > +u32 phy_get_max_link_rate(struct phy *phy); > #else > static inline struct phy *phy_get(struct device *dev, const char *string= ) > { > @@ -256,6 +257,11 @@ static inline int phy_get_bus_width(struct phy *phy) > static inline void phy_set_bus_width(struct phy *phy, int bus_width) > { > } > + > +static inline u32 phy_get_max_link_rate(struct phy *phy) > +{ > + return 0; > +} > #endif /* IS_ENABLED(CONFIG_GENERIC_PHY) */ > =20 > #endif /* __PHY_CONSUMER_H */ --840703edd9f3f1e1e79a02bb78a8d4f69f696b0531524c2c45c8075436e0 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iKMEABYKAEsWIQSJYVVm/x+5xmOiprOFwVZpkBVKUwUCaa6QehsUgAAAAAAEAA5t YW51MiwyLjUrMS4xMiwyLDIRHG1zcEBiYXlsaWJyZS5jb20ACgkQhcFWaZAVSlO3 cwEAzFZFZ21Yi1E3bmSFVrYlzos6oRC2RIJXE4meDDVCTjUA/2INMu045NS1yRGm V6PI/m62S0rUjMso1TupNVful6QE =gdIq -----END PGP SIGNATURE----- --840703edd9f3f1e1e79a02bb78a8d4f69f696b0531524c2c45c8075436e0--