Re: [PATCH 2/3] usb: typec: fsa4480: Add support to swap SBU orientation

[Neil Armstrong]

On 13/10/2023 13:38, Luca Weiss wrote:
> On some hardware designs the AUX+/- lanes are connected reversed to
> SBU1/2 compared to the expected design by FSA4480.
>
> Made more complicated, the otherwise compatible Orient-Chip OCP96011
> expects the lanes to be connected reversed compared to FSA4480.
>
> * FSA4480 block diagram shows AUX+ connected to SBU2 and AUX- to SBU1.
> * OCP96011 block diagram shows AUX+ connected to SBU1 and AUX- to SBU2.
>
> 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.
>
> Support parsing the data-lanes parameter in the endpoint node to swap
> this in the driver.
>
> The parse_data_lanes_mapping function is mostly taken from nb7vpq904m.c.

I see the inspiration :-)

> Signed-off-by: Luca Weiss <luca.weiss@xxxxxxxxxxxxx>
> ---
>   drivers/usb/typec/mux/fsa4480.c | 81 +++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 81 insertions(+)
>
> diff --git a/drivers/usb/typec/mux/fsa4480.c b/drivers/usb/typec/mux/fsa4480.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>
>   #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;
>   
>   	u8 cur_enable;
> +	bool swap_sbu_lanes;
>   };
>   
>   static const struct regmap_config fsa4480_regmap_config = {
> @@ -76,6 +78,9 @@ static int fsa4480_set(struct fsa4480 *fsa)
>   	u8 enable = FSA4480_ENABLE_DEVICE;
>   	u8 sel = 0;
>   
> +	if (fsa->swap_sbu_lanes)
> +		reverse = !reverse;
> +
>   	/* USB Mode */
>   	if (fsa->mode < TYPEC_STATE_MODAL ||
>   	    (!fsa->svid && (fsa->mode == TYPEC_MODE_USB2 ||
> @@ -179,12 +184,84 @@ static int fsa4480_mux_set(struct typec_mux_dev *mux, struct typec_mux_state *st
>   	return ret;
>   }
>   
> +enum {
> +	NORMAL_LANE_MAPPING,
> +	INVERT_LANE_MAPPING,
> +};
> +
> +#define DATA_LANES_COUNT	2
> +
> +static const int supported_data_lane_mapping[][DATA_LANES_COUNT] = {
> +	[NORMAL_LANE_MAPPING] = { 0, 1 },
> +	[INVERT_LANE_MAPPING] = { 1, 0 },
> +};
> +
> +static int fsa4480_parse_data_lanes_mapping(struct fsa4480 *fsa)
> +{
> +	struct device_node *ep;
> +	u32 data_lanes[DATA_LANES_COUNT];
> +	int ret, i, j;
> +
> +	ep = of_graph_get_next_endpoint(fsa->client->dev.of_node, NULL);
> +	if (!ep)
> +		return 0;
> +
> +	ret = of_property_count_u32_elems(ep, "data-lanes");
> +	if (ret == -EINVAL)
> +		/* Property isn't here, consider default mapping */
> +		goto out_done;
> +	if (ret < 0)
> +		goto out_error;
> +
> +	if (ret != DATA_LANES_COUNT) {
> +		dev_err(&fsa->client->dev, "expected 2 data lanes\n");
> +		ret = -EINVAL;
> +		goto out_error;
> +	}
> +
> +	ret = of_property_read_u32_array(ep, "data-lanes", data_lanes, DATA_LANES_COUNT);
> +	if (ret)
> +		goto out_error;
> +
> +	for (i = 0; i < ARRAY_SIZE(supported_data_lane_mapping); i++) {
> +		for (j = 0; j < DATA_LANES_COUNT; j++) {
> +			if (data_lanes[j] != supported_data_lane_mapping[i][j])
> +				break;
> +		}
> +
> +		if (j == DATA_LANES_COUNT)
> +			break;
> +	}
> +
> +	switch (i) {
> +	case NORMAL_LANE_MAPPING:
> +		break;
> +	case INVERT_LANE_MAPPING:
> +		fsa->swap_sbu_lanes = true;
> +		dev_info(&fsa->client->dev, "using inverted data lanes mapping\n");
> +		break;
> +	default:
> +		dev_err(&fsa->client->dev, "invalid data lanes mapping\n");
> +		ret = -EINVAL;
> +		goto out_error;
> +	}
> +
> +out_done:
> +	ret = 0;
> +
> +out_error:
> +	of_node_put(ep);
> +
> +	return ret;
> +}

It's probbaly slighly over engineered for 2 lanes, and at some point
this could go into an helper somewhere because we will need it for all
SBU muxes and redrivers/retimers.

> +
>   static int fsa4480_probe(struct i2c_client *client)
>   {
>   	struct device *dev = &client->dev;
>   	struct typec_switch_desc sw_desc = { };
>   	struct typec_mux_desc mux_desc = { };
>   	struct fsa4480 *fsa;
> +	int ret;
>   
>   	fsa = devm_kzalloc(dev, sizeof(*fsa), GFP_KERNEL);
>   	if (!fsa)
> @@ -193,6 +270,10 @@ static int fsa4480_probe(struct i2c_client *client)
>   	fsa->client = client;
>   	mutex_init(&fsa->lock);
>   
> +	ret = fsa4480_parse_data_lanes_mapping(fsa);
> +	if (ret)
> +		return ret;
> +
>   	fsa->regmap = devm_regmap_init_i2c(client, &fsa4480_regmap_config);
>   	if (IS_ERR(fsa->regmap))
>   		return dev_err_probe(dev, PTR_ERR(fsa->regmap), "failed to initialize regmap\n");

But since I did the same in nb7vpq904m, and the SBU can be inverted, LGTM

Reviewed-by: Neil Armstrong <neil.armstrong@xxxxxxxxxx>

Neil