Message-ID: <aSXR2iEAKjxM8VOR@tom-desktop>
Date: Tue, 25 Nov 2025 16:57:14 +0100
From: Tommaso Merciai <tommaso.merciai.xr@...renesas.com>
To: Geert Uytterhoeven <geert@...ux-m68k.org>
Cc: tomm.merciai@...il.com, linux-renesas-soc@...r.kernel.org,
	biju.das.jz@...renesas.com, Peter Rosin <peda@...ntia.se>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, Vinod Koul <vkoul@...nel.org>,
	Kishon Vijay Abraham I <kishon@...nel.org>,
	Fabrizio Castro <fabrizio.castro.jz@...esas.com>,
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
	Magnus Damm <magnus.damm@...il.com>,
	Sebastian Reichel <sebastian.reichel@...labora.com>,
	Andi Shyti <andi.shyti@...nel.org>,
	Jonathan Cameron <jonathan.cameron@...wei.com>,
	Uwe Kleine-König <ukleinek@...nel.org>,
	Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-phy@...ts.infradead.org
Subject: Re: [PATCH v4 11/22] phy: renesas: rcar-gen3-usb2: Use mux-state for
 phyrst management

Hi Geert,
Thanks for your review!

On Tue, Nov 25, 2025 at 03:10:22PM +0100, Geert Uytterhoeven wrote:
> Hi Tommaso,
> 
> On Fri, 21 Nov 2025 at 16:14, Tommaso Merciai
> <tommaso.merciai.xr@...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@...renesas.com>
> 
> Thanks for your patch!
> 
> > --- 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) {
		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.


Kind Regards,
Tommaso

> 
> > +               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");
> > +       }
> > +
> >         if (channel->phy_data->no_adp_ctrl && channel->is_otg_channel) {
> >                 ret = rcar_gen3_phy_usb2_vbus_regulator_register(channel);
> >                 if (ret)
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> -- 
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-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
> 

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