Re: [PATCH v4 11/22] phy: renesas: rcar-gen3-usb2: Use mux-state for phyrst management

Geert Uytterhoeven
2025-11-26T07:50:15Z

Hi Tommaso,

On Tue, 25 Nov 2025 at 16:57, Tommaso Merciai
<tommaso.merciai.xr@bp.renesas.com> wrote:
> On Tue, Nov 25, 2025 at 03:10:22PM +0100, Geert Uytterhoeven wrote:
> > On Fri, 21 Nov 2025 at 16:14, Tommaso Merciai
> > <tommaso.merciai.xr@bp.renesas.com> wrote:
> > > Add support for selecting the phyrst mux-state using the Linux mux
> > > subsystem in the R-Car Gen3 USB2 PHY driver. This ensures correct hardware
> > > initialization and integration with systems utilizing the mux-state device
> > > tree property.
> > >
> > > A temporary wrapper for optional muxes is introduced until native support
> > > is available in the multiplexer subsystem.
> > >
> > > Signed-off-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>

> > > --- a/drivers/phy/renesas/phy-rcar-gen3-usb2.c
> > > +++ b/drivers/phy/renesas/phy-rcar-gen3-usb2.c
> > > @@ -938,11 +939,27 @@ static int rcar_gen3_phy_usb2_vbus_regulator_register(struct rcar_gen3_chan *cha
> > > return rcar_gen3_phy_usb2_vbus_regulator_get_exclusive_enable(channel, enable);
> > > }
> > >
> > > +/* Temporary wrapper until the multiplexer subsystem supports optional muxes */
> > > +static inline struct mux_state *
> > > +devm_mux_state_get_optional(struct device *dev, const char *mux_name)
> > > +{
> > > + if (!of_property_present(dev->of_node, "mux-states"))
> > > + return NULL;
> > > +
> > > + return devm_mux_state_get(dev, mux_name);
> > > +}
> > > +
> > > +static void rcar_gen3_phy_mux_state_deselect(void *data)
> > > +{
> > > + mux_state_deselect(data);
> > > +}
> > > +
> > > static int rcar_gen3_phy_usb2_probe(struct platform_device *pdev)
> > > {
> > > struct device *dev = &pdev->dev;
> > > struct rcar_gen3_chan *channel;
> > > struct phy_provider *provider;
> > > + struct mux_state *mux_state;
> > > int ret = 0, i, irq;
> > >
> > > if (!dev->of_node) {
> > > @@ -1019,6 +1036,23 @@ static int rcar_gen3_phy_usb2_probe(struct platform_device *pdev)
> > > phy_set_drvdata(channel->rphys[i].phy, &channel->rphys[i]);
> > > }
> > >
> > > + mux_state = devm_mux_state_get_optional(dev, NULL);
> > > + if (IS_ERR(mux_state)) {
> > > + if (PTR_ERR(mux_state) == -EPROBE_DEFER)
> > > + return PTR_ERR(mux_state);
> > > + mux_state = NULL;
> >
> > No need to set mux_state to NULL, as mux_state is not used below.
> >
> > However, shouldn't you propagate all errors up?
> > If the mux is not present, mux_state should already be NULL,
> > i.e. IS_ERR(mux_state) would be false.
> >
> > > + } else {
> > > + ret = mux_state_select(mux_state);
> >
> > This causes a crash on R-Car Gen3 and RZ/Five, as mux_state_select()
> > doesn't handle NULL pointers gracefully yet.
> >
> > Adding a check like
> >
> > - } else {
> > + } else if (mux_state) {
> >
> > fixes the issue.
>
> Thank you for checking this!
>
> Ack :)
> I will switch to:
>
> mux_state = devm_mux_state_get_optional(dev, NULL);
> if (IS_ERR(mux_state)) {
> return PTR_ERR(mux_state);
> } else if (mux_state) {

Please no else after return.

> ret = mux_state_select(mux_state);
> if (ret)
> return dev_err_probe(dev, ret, "Failed to select USB mux\n");
>
> ret = devm_add_action_or_reset(dev, rcar_gen3_phy_mux_state_deselect,
> mux_state);
> if (ret)
> return dev_err_probe(dev, ret,
> "Failed to register USB mux state deselect\n");
> }
>
> In v5.

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds