Hi, On Wed Mar 4, 2026 at 6:57 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. > > 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]> > --- > 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 | 2 +- > drivers/net/can/flexcan/flexcan-core.c | 2 +- > drivers/net/can/m_can/m_can_platform.c | 2 +- > drivers/net/can/rcar/rcar_canfd.c | 2 +- > drivers/phy/phy-core.c | 6 ++++++ > include/linux/phy/phy.h | 6 ++++++ > 8 files changed, 19 insertions(+), 7 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..b56db253f02d 100644 > --- a/drivers/net/can/at91_can.c > +++ b/drivers/net/can/at91_can.c > @@ -1126,7 +1126,7 @@ 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..3a4307bc1d61 100644 > --- a/drivers/net/can/flexcan/flexcan-core.c > +++ b/drivers/net/can/flexcan/flexcan-core.c > @@ -2211,7 +2211,7 @@ static int flexcan_probe(struct platform_device *pdev) > 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..73525be6566b 100644 > --- a/drivers/net/can/m_can/m_can_platform.c > +++ b/drivers/net/can/m_can/m_can_platform.c > @@ -132,7 +132,7 @@ static int m_can_plat_probe(struct platform_device *pdev) > } > > 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..645d5671705d 100644 > --- a/drivers/net/can/rcar/rcar_canfd.c > +++ b/drivers/net/can/rcar/rcar_canfd.c > @@ -1885,7 +1885,7 @@ static int rcar_canfd_channel_probe(struct > rcar_canfd_global *gpriv, u32 ch, > 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 a1aff00fba7c..89f7410241aa 100644 > --- a/drivers/phy/phy-core.c > +++ b/drivers/phy/phy-core.c > @@ -640,6 +640,12 @@ 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) > +{
All of the can drivers that would use this function are checking phy
before assigning the max_link_rate:
if (transceiver)
priv->can.bitrate_max = transceiver->attrs.max_link_rate;
Would it be reasonable to have
if (!phy)
return 0;
in this function to be able to drop these individual checks of the
drivers? This would be similar to clk_get_rate() which does the same
check and return 0 for convenience.
Best
Markus
> + 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 36307e47760d..af9c3e795786 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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