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 <[email protected]> > --- > Cc: Andrzej Hajda <[email protected]> > Cc: Neil Armstrong <[email protected]> > Cc: Robert Foss <[email protected]> > Cc: Laurent Pinchart <[email protected]> > Cc: Jonas Karlman <[email protected]> > Cc: Jernej Skrabec <[email protected]> > Cc: Maarten Lankhorst <[email protected]> > Cc: Maxime Ripard <[email protected]> > Cc: Thomas Zimmermann <[email protected]> > Cc: David Airlie <[email protected]> > Cc: Simona Vetter <[email protected]> > Cc: Andy Yan <[email protected]> > Cc: Marc Kleine-Budde <[email protected]> > Cc: Vincent Mailhol <[email protected]> > Cc: Nicolas Ferre <[email protected]> > Cc: Alexandre Belloni <[email protected]> > Cc: Claudiu Beznea <[email protected]> > Cc: Markus Schneider-Pargmann <[email protected]> > Cc: Geert Uytterhoeven <[email protected]> > Cc: Magnus Damm <[email protected]> > > 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 <[email protected]> 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/drivers/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(struct > cdns_mhdp_device *mhdp, > > static void cdns_mhdp_fill_host_caps(struct cdns_mhdp_device *mhdp) > { > - unsigned int link_rate; > + u32 link_rate; > > /* Get source capabilities based on PHY attributes */ > > @@ -1308,7 +1308,7 @@ static void cdns_mhdp_fill_host_caps(struct > cdns_mhdp_device *mhdp) > if (!mhdp->host.lanes_cnt) > mhdp->host.lanes_cnt = 4; > > - link_rate = mhdp->phy->attrs.max_link_rate; > + link_rate = phy_get_max_link_rate(mhdp->phy); > if (!link_rate) > link_rate = 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/bridge/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) > > link->revision = link->dpcd[DP_DPCD_REV]; > link->rate = 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 = 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 *pdev) > > can_rx_offload_add_timestamp(dev, &priv->offload); > > - if (transceiver) > - priv->can.bitrate_max = transceiver->attrs.max_link_rate; > + priv->can.bitrate_max = phy_get_max_link_rate(transceiver); > > if (at91_is_sam9263(priv)) > dev->sysfs_groups[0] = &at91_sysfs_attr_group; > diff --git a/drivers/net/can/flexcan/flexcan-core.c > b/drivers/net/can/flexcan/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 *pdev) > priv->reg_xceiver = reg_xceiver; > priv->transceiver = transceiver; > > - if (transceiver) > - priv->can.bitrate_max = transceiver->attrs.max_link_rate; > + priv->can.bitrate_max = phy_get_max_link_rate(transceiver); > > if (priv->devtype_data.quirks & FLEXCAN_QUIRK_NR_IRQ_3) { > priv->irq_boff = platform_get_irq(pdev, 1); > diff --git a/drivers/net/can/m_can/m_can_platform.c > b/drivers/net/can/m_can/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 *pdev) > goto probe_fail; > } > > - if (transceiver) > - mcan_class->can.bitrate_max = transceiver->attrs.max_link_rate; > + mcan_class->can.bitrate_max = phy_get_max_link_rate(transceiver); > > priv->base = addr; > priv->mram_base = mram_addr; > diff --git a/drivers/net/can/rcar/rcar_canfd.c > b/drivers/net/can/rcar/rcar_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_canfd_global *gpriv, u32 ch, > priv->transceiver = transceiver; > priv->channel = ch; > priv->gpriv = gpriv; > - if (transceiver) > - priv->can.bitrate_max = transceiver->attrs.max_link_rate; > + priv->can.bitrate_max = phy_get_max_link_rate(transceiver); > priv->can.clock.freq = fcan_freq; > dev_info(dev, "can_clk rate is %u\n", priv->can.clock.freq); > > 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_width) > } > EXPORT_SYMBOL_GPL(phy_set_bus_width); > > +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) */ > > #endif /* __PHY_CONSUMER_H */
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