linux-kernel - Re: [PATCH v2 2/2] usb: typec: Add support for Parade PS8830 Type-C Retimer

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Message-ID: <af5tlrvbceo6gsatkfj4oitznznscxkt7d5lie5mdvu5wky3t3@sktfucncdjnn>
Date: Sun, 6 Oct 2024 18:40:51 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Abel Vesa <abel.vesa@...aro.org>
Cc: Heikki Krogerus <heikki.krogerus@...ux.intel.com>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	linux-arm-msm@...r.kernel.org, Bjorn Andersson <andersson@...nel.org>, 
	Konrad Dybcio <konradybcio@...nel.org>, Rajendra Nayak <quic_rjendra@...cinc.com>, 
	Sibi Sankar <quic_sibis@...cinc.com>, Johan Hovold <johan@...nel.org>, 
	Trilok Soni <quic_tsoni@...cinc.com>, linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org, 
	devicetree@...r.kernel.org
Subject: Re: [PATCH v2 2/2] usb: typec: Add support for Parade PS8830 Type-C
 Retimer

On Fri, Oct 04, 2024 at 04:57:38PM GMT, Abel Vesa wrote:
> The Parade PS8830 is a Type-C muti-protocol retimer controlled over I2C.
> It provides both altmode and orientation handling.
> 
> Add a driver with support for the following modes:
>  - DP 4lanes
>  - DP 2lanes + USB3
>  - USB3
> 
> Signed-off-by: Abel Vesa <abel.vesa@...aro.org>
> ---
>  drivers/usb/typec/mux/Kconfig  |  10 +
>  drivers/usb/typec/mux/Makefile |   1 +
>  drivers/usb/typec/mux/ps8830.c | 424 +++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 435 insertions(+)
> 
> diff --git a/drivers/usb/typec/mux/Kconfig b/drivers/usb/typec/mux/Kconfig
> index ce7db6ad30572a0a74890f5f11944fb3ff07f635..48613b67f1c5dacd14d54baf91c3066377cf97be 100644
> --- a/drivers/usb/typec/mux/Kconfig
> +++ b/drivers/usb/typec/mux/Kconfig
> @@ -56,6 +56,16 @@ config TYPEC_MUX_NB7VPQ904M
>  	  Say Y or M if your system has a On Semiconductor NB7VPQ904M Type-C
>  	  redriver chip found on some devices with a Type-C port.
>  
> +config TYPEC_MUX_PS8830
> +	tristate "Parade PS8830 Type-C retimer driver"
> +	depends on I2C
> +	depends on DRM || DRM=n
> +	select DRM_AUX_BRIDGE if DRM_BRIDGE && OF
> +	select REGMAP_I2C
> +	help
> +	  Say Y or M if your system has a Parade PS8830 Type-C retimer chip
> +	  found on some devices with a Type-C port.
> +
>  config TYPEC_MUX_PTN36502
>  	tristate "NXP PTN36502 Type-C redriver driver"
>  	depends on I2C
> diff --git a/drivers/usb/typec/mux/Makefile b/drivers/usb/typec/mux/Makefile
> index bb96f30267af05b33b9277dcf1cc0e1527d2dcdd..4b23b12cfe45a0ff8a37f38c7ba050f572d556e7 100644
> --- a/drivers/usb/typec/mux/Makefile
> +++ b/drivers/usb/typec/mux/Makefile
> @@ -6,5 +6,6 @@ obj-$(CONFIG_TYPEC_MUX_PI3USB30532)	+= pi3usb30532.o
>  obj-$(CONFIG_TYPEC_MUX_INTEL_PMC)	+= intel_pmc_mux.o
>  obj-$(CONFIG_TYPEC_MUX_IT5205)		+= it5205.o
>  obj-$(CONFIG_TYPEC_MUX_NB7VPQ904M)	+= nb7vpq904m.o
> +obj-$(CONFIG_TYPEC_MUX_PS8830)		+= ps8830.o
>  obj-$(CONFIG_TYPEC_MUX_PTN36502)	+= ptn36502.o
>  obj-$(CONFIG_TYPEC_MUX_WCD939X_USBSS)	+= wcd939x-usbss.o
> diff --git a/drivers/usb/typec/mux/ps8830.c b/drivers/usb/typec/mux/ps8830.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..58990f7860bf77ec12d00f0d3df3a40735bbf9d8
> --- /dev/null
> +++ b/drivers/usb/typec/mux/ps8830.c
> @@ -0,0 +1,424 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Parade PS8830 usb retimer driver
> + *
> + * Copyright (C) 2024 Linaro Ltd.
> + */
> +
> +#include <drm/bridge/aux-bridge.h>
> +#include <linux/clk.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/i2c.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/regmap.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/usb/typec_altmode.h>
> +#include <linux/usb/typec_dp.h>
> +#include <linux/usb/typec_mux.h>
> +#include <linux/usb/typec_retimer.h>
> +
> +struct ps8830_retimer {
> +	struct i2c_client *client;
> +	struct gpio_desc *reset_gpio;
> +	struct regmap *regmap;
> +	struct typec_switch_dev *sw;
> +	struct typec_retimer *retimer;
> +	struct clk *xo_clk;
> +	struct regulator *vdd_supply;
> +	struct regulator *vdd33_supply;
> +	struct regulator *vdd33_cap_supply;
> +	struct regulator *vddat_supply;
> +	struct regulator *vddar_supply;
> +	struct regulator *vddio_supply;
> +
> +	struct typec_switch *typec_switch;
> +	struct typec_mux *typec_mux;
> +
> +	struct mutex lock; /* protect non-concurrent retimer & switch */
> +
> +	enum typec_orientation orientation;
> +	unsigned long mode;
> +	int cfg[3];
> +};
> +
> +static void ps8830_write(struct ps8830_retimer *retimer, int cfg0, int cfg1, int cfg2)
> +{
> +	if (cfg0 == retimer->cfg[0] &&
> +	    cfg1 == retimer->cfg[1] &&
> +	    cfg2 == retimer->cfg[2])
> +		return;
> +
> +	retimer->cfg[0] = cfg0;
> +	retimer->cfg[1] = cfg1;
> +	retimer->cfg[2] = cfg2;
> +
> +	regmap_write(retimer->regmap, 0x0, cfg0);
> +	regmap_write(retimer->regmap, 0x1, cfg1);
> +	regmap_write(retimer->regmap, 0x2, cfg2);
> +}

This looks like a reimplementation of regcache. Is it really necessary?

> +
> +static void ps8830_configure(struct ps8830_retimer *retimer, int cfg0, int cfg1, int cfg2)
> +{
> +	/* Write safe-mode config before switching to new config */

Why is this required?

> +	ps8830_write(retimer, 0x1, 0x0, 0x0);
> +
> +	ps8830_write(retimer, cfg0, cfg1, cfg2);
> +}
> +
> +static int ps8380_set(struct ps8830_retimer *retimer)
> +{
> +	int cfg0 = 0x00;
> +	int cfg1 = 0x00;
> +	int cfg2 = 0x00;
> +
> +	if (retimer->orientation == TYPEC_ORIENTATION_NONE ||
> +	    retimer->mode == TYPEC_STATE_SAFE) {
> +		ps8830_write(retimer, 0x1, 0x0, 0x0);
> +		return 0;
> +	}
> +
> +	if (retimer->orientation == TYPEC_ORIENTATION_NORMAL)
> +		cfg0 = 0x01;
> +	else
> +		cfg0 = 0x03;
> +
> +	switch (retimer->mode) {
> +	/* USB3 Only */
> +	case TYPEC_STATE_USB:
> +		cfg0 |= 0x20;
> +		break;
> +

The TYPEC_DP clauses should only be used if state->alt->swid is set to
USB_TYPEC_DP_SID. Other altmodes share id space for their states.

> +	/* DP Only */
> +	case TYPEC_DP_STATE_C:
> +		cfg1 = 0x85;
> +		break;
> +
> +	case TYPEC_DP_STATE_E:
> +		cfg1 = 0x81;
> +		break;
> +
> +	/* DP + USB */
> +	case TYPEC_DP_STATE_D:
> +		cfg0 |= 0x20;
> +		cfg1 = 0x85;
> +		break;

CDE, please.

> +
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +
> +	ps8830_configure(retimer, cfg0, cfg1, cfg2);
> +
> +	return 0;
> +}
> +

-- 
With best wishes
Dmitry