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Date:   Tue, 17 Oct 2023 12:17:42 +0200
Message-Id: <CWAMY8EP9RN1.VPH5E7Z1T7JN@fairphone.com>
Subject: Re: [PATCH 2/3] usb: typec: fsa4480: Add support to swap SBU
 orientation
From:   "Luca Weiss" <luca.weiss@fairphone.com>
To:     "Heikki Krogerus" <heikki.krogerus@linux.intel.com>
Cc:     "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
        "Neil Armstrong" <neil.armstrong@linaro.org>,
        "Rob Herring" <robh+dt@kernel.org>,
        "Krzysztof Kozlowski" <krzysztof.kozlowski+dt@linaro.org>,
        "Conor Dooley" <conor+dt@kernel.org>,
        "Bjorn Andersson" <andersson@kernel.org>,
        <~postmarketos/upstreaming@lists.sr.ht>,
        <phone-devel@vger.kernel.org>, <linux-usb@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <linux-arm-msm@vger.kernel.org>,
        <devicetree@vger.kernel.org>
References: <20231013-fsa4480-swap-v1-0-b877f62046cc@fairphone.com>
 <20231013-fsa4480-swap-v1-2-b877f62046cc@fairphone.com>
 <ZS5NV43MhD3YNeDX@kuha.fi.intel.com>
In-Reply-To: <ZS5NV43MhD3YNeDX@kuha.fi.intel.com>
Precedence: bulk

On Tue Oct 17, 2023 at 11:01 AM CEST, Heikki Krogerus wrote:
> Hi Luca,
>
> On Fri, Oct 13, 2023 at 01:38:06PM +0200, Luca Weiss wrote:
> > On some hardware designs the AUX+/- lanes are connected reversed to
> > SBU1/2 compared to the expected design by FSA4480.
> >=20
> > Made more complicated, the otherwise compatible Orient-Chip OCP96011
> > expects the lanes to be connected reversed compared to FSA4480.
> >=20
> > * FSA4480 block diagram shows AUX+ connected to SBU2 and AUX- to SBU1.
> > * OCP96011 block diagram shows AUX+ connected to SBU1 and AUX- to SBU2.
> >=20
> > So if OCP96011 is used as drop-in for FSA4480 then the orientation
> > handling in the driver needs to be reversed to match the expectation of
> > the OCP96011 hardware.
> >=20
> > Support parsing the data-lanes parameter in the endpoint node to swap
> > this in the driver.
> >=20
> > The parse_data_lanes_mapping function is mostly taken from nb7vpq904m.c=
.
> >=20
> > Signed-off-by: Luca Weiss <luca.weiss@fairphone.com>
> > ---
> >  drivers/usb/typec/mux/fsa4480.c | 81 +++++++++++++++++++++++++++++++++=
++++++++
> >  1 file changed, 81 insertions(+)
> >=20
> > diff --git a/drivers/usb/typec/mux/fsa4480.c b/drivers/usb/typec/mux/fs=
a4480.c
> > index e0ee1f621abb..6ee467c96fb6 100644
> > --- a/drivers/usb/typec/mux/fsa4480.c
> > +++ b/drivers/usb/typec/mux/fsa4480.c
> > @@ -9,6 +9,7 @@
> >  #include <linux/kernel.h>
> >  #include <linux/module.h>
> >  #include <linux/mutex.h>
> > +#include <linux/of_graph.h>
>
> If you don't mind, let's keep this driver ready for ACPI, just in
> case...

I'm quite clueless about any details about ACPI but makes sense to use
the generic APIs.

>
> >  #include <linux/regmap.h>
> >  #include <linux/usb/typec_dp.h>
> >  #include <linux/usb/typec_mux.h>
> > @@ -60,6 +61,7 @@ struct fsa4480 {
> >  	unsigned int svid;
> > =20
> >  	u8 cur_enable;
> > +	bool swap_sbu_lanes;
> >  };
> > =20
> >  static const struct regmap_config fsa4480_regmap_config =3D {
> > @@ -76,6 +78,9 @@ static int fsa4480_set(struct fsa4480 *fsa)
> >  	u8 enable =3D FSA4480_ENABLE_DEVICE;
> >  	u8 sel =3D 0;
> > =20
> > +	if (fsa->swap_sbu_lanes)
> > +		reverse =3D !reverse;
> > +
> >  	/* USB Mode */
> >  	if (fsa->mode < TYPEC_STATE_MODAL ||
> >  	    (!fsa->svid && (fsa->mode =3D=3D TYPEC_MODE_USB2 ||
> > @@ -179,12 +184,84 @@ static int fsa4480_mux_set(struct typec_mux_dev *=
mux, struct typec_mux_state *st
> >  	return ret;
> >  }
> > =20
> > +enum {
> > +	NORMAL_LANE_MAPPING,
> > +	INVERT_LANE_MAPPING,
> > +};
> > +
> > +#define DATA_LANES_COUNT	2
> > +
> > +static const int supported_data_lane_mapping[][DATA_LANES_COUNT] =3D {
> > +	[NORMAL_LANE_MAPPING] =3D { 0, 1 },
> > +	[INVERT_LANE_MAPPING] =3D { 1, 0 },
> > +};
> > +
> > +static int fsa4480_parse_data_lanes_mapping(struct fsa4480 *fsa)
> > +{
> > +	struct device_node *ep;
>
>         struct fwnode_handle *ep;
>
> > +	u32 data_lanes[DATA_LANES_COUNT];
> > +	int ret, i, j;
> > +
> > +	ep =3D of_graph_get_next_endpoint(fsa->client->dev.of_node, NULL);
>
> Shouldn't you loop through the endpoints? In any case:
>
>         ep =3D fwnode_graph_get_next_endpoint(dev_fwnode(&fsa->client->de=
v, NULL));

The docs only mention one endpoint so I'm assuming just next_endpoint is
fine?

>
> > +	if (!ep)
> > +		return 0;
> > +
> > +	ret =3D of_property_count_u32_elems(ep, "data-lanes");
>
>         ret =3D fwnode_property_count_u32(ep, "data-lanes");
>
> But is this necessary at all in this case - why not just read the
> array since you expect a fixed size for it (if the read fails it fails)?

Hm yeah that should be okay.. Will check the docs
of_property_read_u32_array (or well fwnode_property_read_u32_array) to
see if there's any gotchas if there's less or more elements provided.

Regards
Luca

>
> > +	if (ret =3D=3D -EINVAL)
> > +		/* Property isn't here, consider default mapping */
> > +		goto out_done;
> > +	if (ret < 0)
> > +		goto out_error;
> > +
> > +	if (ret !=3D DATA_LANES_COUNT) {
> > +		dev_err(&fsa->client->dev, "expected 2 data lanes\n");
> > +		ret =3D -EINVAL;
> > +		goto out_error;
> > +	}
> > +
> > +	ret =3D of_property_read_u32_array(ep, "data-lanes", data_lanes, DATA=
_LANES_COUNT);
>
>         ret =3D fwnode_property_read_u32_array(ep, "data-lanes", data_lan=
es, DATA_LANES_COUNT);
>
> > +	if (ret)
> > +		goto out_error;
> > +
> > +	for (i =3D 0; i < ARRAY_SIZE(supported_data_lane_mapping); i++) {
> > +		for (j =3D 0; j < DATA_LANES_COUNT; j++) {
> > +			if (data_lanes[j] !=3D supported_data_lane_mapping[i][j])
> > +				break;
> > +		}
> > +
> > +		if (j =3D=3D DATA_LANES_COUNT)
> > +			break;
> > +	}
> > +
> > +	switch (i) {
> > +	case NORMAL_LANE_MAPPING:
> > +		break;
> > +	case INVERT_LANE_MAPPING:
> > +		fsa->swap_sbu_lanes =3D true;
> > +		dev_info(&fsa->client->dev, "using inverted data lanes mapping\n");
>
> That is just noise. Please drop it.
>
> > +		break;
> > +	default:
> > +		dev_err(&fsa->client->dev, "invalid data lanes mapping\n");
> > +		ret =3D -EINVAL;
> > +		goto out_error;
> > +	}
> > +
> > +out_done:
> > +	ret =3D 0;
> > +
> > +out_error:
> > +	of_node_put(ep);
> > +
> > +	return ret;
> > +}
> > +
> >  static int fsa4480_probe(struct i2c_client *client)
> >  {
> >  	struct device *dev =3D &client->dev;
> >  	struct typec_switch_desc sw_desc =3D { };
> >  	struct typec_mux_desc mux_desc =3D { };
> >  	struct fsa4480 *fsa;
> > +	int ret;
> > =20
> >  	fsa =3D devm_kzalloc(dev, sizeof(*fsa), GFP_KERNEL);
> >  	if (!fsa)
> > @@ -193,6 +270,10 @@ static int fsa4480_probe(struct i2c_client *client=
)
> >  	fsa->client =3D client;
> >  	mutex_init(&fsa->lock);
> > =20
> > +	ret =3D fsa4480_parse_data_lanes_mapping(fsa);
> > +	if (ret)
> > +		return ret;
> > +
> >  	fsa->regmap =3D devm_regmap_init_i2c(client, &fsa4480_regmap_config);
> >  	if (IS_ERR(fsa->regmap))
> >  		return dev_err_probe(dev, PTR_ERR(fsa->regmap), "failed to initializ=
e regmap\n");
> >=20
> > --=20
> > 2.42.0