RE: [PATCH v10 5/6] usb:cdns3 Add Cadence USB3 DRD Driver

[Pawel Laszczak <pawell@cadence.com>]

Hi,

>
>On 21/07/2019 21:32, Pawel Laszczak wrote:
>> This patch introduce new Cadence USBSS DRD driver to Linux kernel.
>>
>> The Cadence USBSS DRD Controller is a highly configurable IP Core which
>> can be instantiated as Dual-Role Device (DRD), Peripheral Only and
>> Host Only (XHCI)configurations.
>>
>> The current driver has been validated with FPGA platform. We have
>> support for PCIe bus, which is used on FPGA prototyping.
>>
>> The host side of USBSS-DRD controller is compliant with XHCI
>> specification, so it works with standard XHCI Linux driver.
>>
>> Signed-off-by: Pawel Laszczak <pawell@cadence.com>
>> ---
>>  drivers/usb/Kconfig                |    2 +
>>  drivers/usb/Makefile               |    2 +
>>  drivers/usb/cdns3/Kconfig          |   46 +
>>  drivers/usb/cdns3/Makefile         |   17 +
>>  drivers/usb/cdns3/cdns3-pci-wrap.c |  203 +++
>>  drivers/usb/cdns3/core.c           |  554 +++++++
>>  drivers/usb/cdns3/core.h           |  109 ++
>>  drivers/usb/cdns3/debug.h          |  171 ++
>>  drivers/usb/cdns3/debugfs.c        |   87 ++
>>  drivers/usb/cdns3/drd.c            |  390 +++++
>>  drivers/usb/cdns3/drd.h            |  166 ++
>>  drivers/usb/cdns3/ep0.c            |  914 +++++++++++
>>  drivers/usb/cdns3/gadget-export.h  |   28 +
>>  drivers/usb/cdns3/gadget.c         | 2338 ++++++++++++++++++++++++++++
>>  drivers/usb/cdns3/gadget.h         | 1321 ++++++++++++++++
>>  drivers/usb/cdns3/host-export.h    |   28 +
>>  drivers/usb/cdns3/host.c           |   71 +
>>  drivers/usb/cdns3/trace.c          |   11 +
>>  drivers/usb/cdns3/trace.h          |  493 ++++++
>>  19 files changed, 6951 insertions(+)
>>  create mode 100644 drivers/usb/cdns3/Kconfig
>>  create mode 100644 drivers/usb/cdns3/Makefile
>>  create mode 100644 drivers/usb/cdns3/cdns3-pci-wrap.c
>>  create mode 100644 drivers/usb/cdns3/core.c
>>  create mode 100644 drivers/usb/cdns3/core.h
>>  create mode 100644 drivers/usb/cdns3/debug.h
>>  create mode 100644 drivers/usb/cdns3/debugfs.c
>>  create mode 100644 drivers/usb/cdns3/drd.c
>>  create mode 100644 drivers/usb/cdns3/drd.h
>>  create mode 100644 drivers/usb/cdns3/ep0.c
>>  create mode 100644 drivers/usb/cdns3/gadget-export.h
>>  create mode 100644 drivers/usb/cdns3/gadget.c
>>  create mode 100644 drivers/usb/cdns3/gadget.h
>>  create mode 100644 drivers/usb/cdns3/host-export.h
>>  create mode 100644 drivers/usb/cdns3/host.c
>>  create mode 100644 drivers/usb/cdns3/trace.c
>>  create mode 100644 drivers/usb/cdns3/trace.h
>>
>
><snip>
>
>> diff --git a/drivers/usb/cdns3/core.c b/drivers/usb/cdns3/core.c
>> new file mode 100644
>> index 000000000000..900b2ce08162
>> --- /dev/null
>> +++ b/drivers/usb/cdns3/core.c
>> @@ -0,0 +1,554 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Cadence USBSS DRD Driver.
>> + *
>> + * Copyright (C) 2018-2019 Cadence.
>> + * Copyright (C) 2017-2018 NXP
>> + * Copyright (C) 2019 Texas Instruments
>> + *
>> + * Author: Peter Chen <peter.chen@nxp.com>
>> + *         Pawel Laszczak <pawell@cadence.com>
>> + *         Roger Quadros <rogerq@ti.com>
>> + */
>> +
>> +#include <linux/dma-mapping.h>
>> +#include <linux/module.h>
>> +#include <linux/kernel.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/io.h>
>> +#include <linux/pm_runtime.h>
>> +
>> +#include "gadget.h"
>> +#include "core.h"
>> +#include "host-export.h"
>> +#include "gadget-export.h"
>> +#include "drd.h"
>> +#include "debug.h"
>> +
>> +static inline
>> +struct cdns3_role_driver *cdns3_get_current_role_driver(struct cdns3 *cdns)
>> +{
>> +	WARN_ON(!cdns->roles[cdns->role]);
>> +	return cdns->roles[cdns->role];
>> +}
>> +
>> +static int cdns3_role_start(struct cdns3 *cdns, enum usb_role role)
>> +{
>> +	int ret;
>> +
>> +	if (WARN_ON(role > USB_ROLE_DEVICE))
>> +		return 0;
>> +
>> +	mutex_lock(&cdns->mutex);
>> +	cdns->role = role;
>> +	mutex_unlock(&cdns->mutex);
>> +
>> +	if (role == USB_ROLE_NONE)
>> +		return 0;
>
>We will need to have a role driver for NONE case so we can deal with
>type-C cable swap case. I will post a patch at the end about this.
>You can squash the patches and use them in the next revision.

>
>> +
>> +	if (!cdns->roles[role])
>> +		return -ENXIO;
>> +
>> +	if (cdns->roles[role]->state == CDNS3_ROLE_STATE_ACTIVE)
>> +		return 0;
>> +
>> +	mutex_lock(&cdns->mutex);
>> +	if (role == USB_ROLE_HOST)
>> +		cdns3_drd_switch_host(cdns, 1);
>> +	else
>> +		cdns3_drd_switch_gadget(cdns, 1);
>
>Please don't do this here. You can call them from the respective role
>drivers at the start. i.e. __cdns3_host_init(), __cdns3_gadget_init()

Why it can't do this here?

Do we really want to mix  drd code with gadget/host ?

>> +
>> +	ret = cdns->roles[role]->start(cdns);
>> +	if (!ret)
>> +		cdns->roles[role]->state = CDNS3_ROLE_STATE_ACTIVE;
>> +	mutex_unlock(&cdns->mutex);
>> +
>> +	return ret;
>> +}
>> +
>> +static void cdns3_role_stop(struct cdns3 *cdns)
>> +{
>> +	enum usb_role role = cdns->role;
>> +
>> +	if (WARN_ON(role > USB_ROLE_DEVICE))
>> +		return;
>> +
>> +	if (role == USB_ROLE_NONE)
>> +		return;
>> +
>> +	if (cdns->roles[role]->state == CDNS3_ROLE_STATE_INACTIVE)
>> +		return;
>> +
>> +	mutex_lock(&cdns->mutex);
>> +	cdns->roles[role]->stop(cdns);
>> +	if (role == USB_ROLE_HOST)
>> +		cdns3_drd_switch_host(cdns, 0);
>> +	else
>> +		cdns3_drd_switch_gadget(cdns, 0);
>
>No need to do this here. They can be done at the respective role
>drivers at the end. i.e. cdns3_host_exit(), cdns3_gadget_exit()
>
>> +
>> +	cdns->roles[role]->state = CDNS3_ROLE_STATE_INACTIVE;
>> +	mutex_unlock(&cdns->mutex);
>> +}
>> +
>> +static void cdns3_exit_roles(struct cdns3 *cdns)
>> +{
>> +	cdns3_role_stop(cdns);
>> +	cdns3_drd_exit(cdns);
>> +}
>> +
>> +enum usb_role cdsn3_real_role_switch_get(struct device *dev);
>> +
>> +/**
>> + * cdns3_core_init_role - initialize role of operation
>> + * @cdns: Pointer to cdns3 structure
>> + *
>> + * Returns 0 on success otherwise negative errno
>> + */
>> +static int cdns3_core_init_role(struct cdns3 *cdns)
>> +{
>> +	struct device *dev = cdns->dev;
>> +	enum usb_dr_mode best_dr_mode;
>> +	enum usb_dr_mode dr_mode;
>> +	int ret = 0;
>> +
>> +	dr_mode = usb_get_dr_mode(dev);
>> +	cdns->role = USB_ROLE_NONE;
>> +
>> +	/*
>> +	 * If driver can't read mode by means of usb_get_dr_mode function then
>> +	 * chooses mode according with Kernel configuration. This setting
>> +	 * can be restricted later depending on strap pin configuration.
>> +	 */
>> +	if (dr_mode == USB_DR_MODE_UNKNOWN) {
>> +		if (IS_ENABLED(CONFIG_USB_CDNS3_HOST) &&
>> +		    IS_ENABLED(CONFIG_USB_CDNS3_GADGET))
>> +			dr_mode = USB_DR_MODE_OTG;
>> +		else if (IS_ENABLED(CONFIG_USB_CDNS3_HOST))
>> +			dr_mode = USB_DR_MODE_HOST;
>> +		else if (IS_ENABLED(CONFIG_USB_CDNS3_GADGET))
>> +			dr_mode = USB_DR_MODE_PERIPHERAL;
>> +	}
>> +
>> +	/*
>> +	 * At this point cdns->dr_mode contains strap configuration.
>> +	 * Driver try update this setting considering kernel configuration
>> +	 */
>> +	best_dr_mode = cdns->dr_mode;
>> +
>> +	if (dr_mode == USB_DR_MODE_OTG) {
>> +		best_dr_mode = cdns->dr_mode;
>> +	} else if (cdns->dr_mode == USB_DR_MODE_OTG) {
>> +		best_dr_mode = dr_mode;
>> +	} else if (cdns->dr_mode != dr_mode) {
>> +		dev_err(dev, "Incorrect DRD configuration\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	dr_mode = best_dr_mode;
>> +
>> +	if (dr_mode == USB_DR_MODE_OTG || dr_mode == USB_DR_MODE_HOST) {
>> +		ret = cdns3_host_init(cdns);
>> +		if (ret) {
>> +			dev_err(dev, "Host initialization failed with %d\n",
>> +				ret);
>> +			goto err;
>> +		}
>> +	}
>> +
>> +	if (dr_mode == USB_DR_MODE_OTG || dr_mode == USB_DR_MODE_PERIPHERAL) {
>> +		ret = cdns3_gadget_init(cdns);
>> +		if (ret) {
>> +			dev_err(dev, "Device initialization failed with %d\n",
>> +				ret);
>> +			goto err;
>> +		}
>> +	}
>> +
>> +	cdns->desired_dr_mode = dr_mode;
>> +	cdns->dr_mode = dr_mode;
>> +
>> +	/*
>> +	 * desired_dr_mode might have changed so we need to update
>> +	 * the controller configuration"?
>> +	 */
>> +	ret = cdns3_drd_update_mode(cdns);
>> +	if (ret)
>> +		goto err;
>> +
>> +	cdns->role = cdsn3_real_role_switch_get(cdns->dev);
>> +
>> +	ret = cdns3_role_start(cdns, cdns->role);
>> +	if (ret) {
>> +		dev_err(dev, "can't start %s role\n",
>> +			cdns3_get_current_role_driver(cdns)->name);
>> +		goto err;
>> +	}
>> +
>> +	return ret;
>> +err:
>> +	cdns3_exit_roles(cdns);
>> +	return ret;
>> +}
>> +
>> +/**
>> + * cdsn3_real_role_switch_get - get real role of controller based on hardware
>> + *   settings.
>> + * @dev: Pointer to device structure
>> + *
>> + * Returns role
>> + */
>> +enum usb_role cdsn3_real_role_switch_get(struct device *dev)
>
>let's not mix user space role_switch and HW based role swith.
>
>This function is really the HW based state machine. Let's rename it to
>
> * cdsn3_hw_role_state_machine - role switch state machine based on hw events
> *
> * @cdns: Pointer to controller structure
> *
> * Returns next role to be entered based on hw events.
> */
>static enum usb_role cdsn3_hw_role_state_machine(struct cdns3 *cdns)
>
>> +{
>> +	struct cdns3 *cdns = dev_get_drvdata(dev);
>> +	enum usb_role role;
>> +	int id, vbus;
>> +
>> +	if (cdns->current_dr_mode != USB_DR_MODE_OTG)
>> +		goto not_otg;
>> +
>> +	id = cdns3_get_id(cdns);
>> +	vbus = cdns3_get_vbus(cdns);
>> +
>> +	/*
>> +	 * Role change state machine
>> +	 * Inputs: ID, VBUS
>> +	 * Previous state: cdns->role
>> +	 * Next state: role
>> +	 */
>> +	role = cdns->role;
>> +
>> +	switch (role) {
>> +	case USB_ROLE_NONE:
>> +		/*
>> +		 * Driver treat USB_ROLE_NONE synonymous to IDLE state from
>
>s/treat/treats
>
>> +		 * controller specification.
>> +		 */
>> +		if (!id)
>> +			role = USB_ROLE_HOST;
>> +		else if (vbus)
>> +			role = USB_ROLE_DEVICE;
>> +		break;
>> +	case USB_ROLE_HOST: /* from HOST, we can only change to NONE */
>> +		if (id)
>> +			role = USB_ROLE_NONE;
>> +		break;
>> +	case USB_ROLE_DEVICE: /* from GADGET, we can only change to NONE*/
>> +		if (!vbus)
>> +			role = USB_ROLE_NONE;
>> +		break;
>> +	}
>> +
>> +	dev_dbg(cdns->dev, "role %d -> %d\n", cdns->role, role);
>> +
>> +	return role;
>> +
>> +not_otg:
>> +	if (cdns3_is_host(cdns))
>> +		role = USB_ROLE_HOST;
>> +	if (cdns3_is_device(cdns))
>> +		role = USB_ROLE_DEVICE;
>> +
>> +	return role;
>> +}
>> +
>> +/**
>> + * cdns3_role_switch_set - work queue handler for role switch
>> + *
>> + * @dev: pointer to device object
>> + * @role - the previous role
>> + * Handles below events:
>> + * - Role switch for dual-role devices
>> + * - USB_ROLE_GADGET <--> USB_ROLE_NONE for peripheral-only devices
>> + */
>> +static int cdns3_role_switch_set(struct device *dev, enum usb_role role)
>
>Let's not use this for user space role switch but just for HW based switching
>How about calling it
>
>int cdns3_hw_role_switch(struct cdns3 *cdns)

Ok, I will change name.

>
>> +{
>> +	struct cdns3 *cdns = dev_get_drvdata(dev);
>> +	enum usb_role real_role = USB_ROLE_NONE;
>> +	enum usb_role current_role;
>
>enum usb_role real_role, current_role;
>
>> +	int ret = 0;
>> +
>> +	/* Check if dr_mode was changed.*/
>> +	ret = cdns3_drd_update_mode(cdns);
>

After removing debugfs it's not longer needed. 

>Why is this check required? Who is going to change dr_mode?
>
>> +	if (ret)
>> +		return ret;
>
>I think here we need to check if user overrides the role
>using role switch sysfs. If yes then we ned ignore HW events
>and just return here.

Should I add some extra flags for detecting this in CDNS3 driver 
or we should assume that it will be added in role switch framework ?

>
>> +
>> +	pm_runtime_get_sync(cdns->dev);
>> +
>> +	real_role = cdsn3_real_role_switch_get(cdns->dev);
>
>       current_role = cdns->role;
>       real_role = cdsn3_hw_role_state_machine(cdns);
>
>> +
>> +	/* Do nothing if nothing changed */
>> +	if (cdns->role == real_role)
>
>	if (current_role == real_role)
>
>> +		goto exit;
>> +
>> +	cdns3_role_stop(cdns);
>> +
>> +	real_role = cdsn3_real_role_switch_get(cdns->dev);
>> +
>> +	current_role = role;
>
>Remove above 2 lines. Don't need to get real role again
>here as it will break the state machine.
>If HW state changes, we will deal with it in next interrupt
>not here.
>
>> +	dev_dbg(cdns->dev, "Switching role");
>
>	dev_dbg(cdns->dev, "Switching role %d -> %d", current_role, real_role);
>
>> +
>> +	ret = cdns3_role_start(cdns, real_role);
>> +	if (ret) {
>> +		/* Back to current role */
>> +		dev_err(cdns->dev, "set %d has failed, back to %d\n",
>> +			role, current_role);
>
>			real_role, current_role
>
>> +		ret = cdns3_role_start(cdns, current_role);
>> +		if (ret)
>> +			dev_err(cdns->dev, "back to %d failed too\n",
>> +				current_role);
>> +	}
>> +exit:
>> +	pm_runtime_put_sync(cdns->dev);
>> +	return ret;
>> +}
>
>How about the below 2 functions for user space role switch handling.
>
>+/**
>+ * cdsn3_role_get - get current role of controller.
>+ *
>+ * @dev: Pointer to device structure
>+ *
>+ * Returns role
>+ */
>+static enum usb_role cdns3_role_get(struct device *dev)
>+{
>+       struct cdns3 *cdns = dev_get_drvdata(dev);
>+
>+       return cdns->role;
>+}
>+
>+/**
>+ * cdns3_role_set - set current role of controller.
>+ *
>+ * @dev: pointer to device object
>+ * @role - the previous role
>+ * Handles below events:
>+ * - Role switch for dual-role devices
>+ * - USB_ROLE_GADGET <--> USB_ROLE_NONE for peripheral-only devices
>+ */
>+static int cdns3_role_set(struct device *dev, enum usb_role role)
>+{
>+       /* FIXME: doing nothing for now */
>
>Here we need to implement the user space switching logic.
>
>1) If called change to desired role and set a userspace override flag
>2) How do we clear the userspace override flag so HW based switching can
>continue? Need new API hook in struct usb_role_switch_desc?
>
>+       return -EPERM;
>+}
>+

But Felipe will complain for this empty function :).

>> +
>> +static const struct usb_role_switch_desc cdns3_switch_desc = {
>> +	.set = cdns3_role_switch_set,
>> +	.get = cdsn3_real_role_switch_get,
>
>       .set = cdns3_role_set,
>       .get = cdns3_role_get,
>
>> +	.allow_userspace_control = true,
>> +};
>> +
>
><snip>
>
>> diff --git a/drivers/usb/cdns3/drd.c b/drivers/usb/cdns3/drd.c
>> new file mode 100644
>> index 000000000000..77f8a1516140
>> --- /dev/null
>> +++ b/drivers/usb/cdns3/drd.c
>> @@ -0,0 +1,390 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Cadence USBSS DRD Driver.
>> + *
>> + * Copyright (C) 2018-2019 Cadence.
>> + * Copyright (C) 2019 Texas Instruments
>> + *
>> + * Author: Pawel Laszczak <pawell@cadence.com>
>> + *         Roger Quadros <rogerq@ti.com>
>> + *
>> + *
>> + */
>> +#include <linux/kernel.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/delay.h>
>> +#include <linux/iopoll.h>
>> +#include <linux/usb/otg.h>
>> +
>> +#include "gadget.h"
>> +#include "drd.h"
>> +#include "core.h"
>> +
>
><snip>
>
>> +/**
>> + * cdns3_drd_update_mode - initialize mode of operation
>> + * @cdns: Pointer to controller context structure
>> + *
>> + * Returns 0 on success otherwise negative errno
>> + */
>> +int cdns3_drd_update_mode(struct cdns3 *cdns)
>> +{
>> +	int ret = 0;
>> +
>> +	if (cdns->desired_dr_mode == cdns->current_dr_mode)
>> +		return ret;
>> +
>> +	switch (cdns->desired_dr_mode) {
>> +	case USB_DR_MODE_PERIPHERAL:
>> +		ret = cdns3_set_mode(cdns, USB_DR_MODE_PERIPHERAL);
>> +		break;
>> +	case USB_DR_MODE_HOST:
>> +		ret = cdns3_set_mode(cdns, USB_DR_MODE_HOST);
>> +		break;
>> +	case USB_DR_MODE_OTG:
>> +		ret = cdns3_init_otg_mode(cdns);
>> +		break;
>> +	default:
>> +		dev_err(cdns->dev, "Unsupported mode of operation %d\n",
>> +			cdns->dr_mode);
>> +		return -EINVAL;
>> +	}
>> +
>> +	return ret;
>> +}
>> +
>> +static irqreturn_t cdns3_drd_thread_irq(int irq, void *data)
>> +{
>> +	struct cdns3 *cdns = data;
>> +
>> +	usb_role_switch_set_role(cdns->role_sw, cdns->role);
>> +
>	This is HW based event. Don't mix this with user space role switch.
>	So,
>
>	cdns3_hw_role_switch(cdns);
>
>> +	return IRQ_HANDLED;
>> +}
>> +
>
><snip>
>
>The below 2 patches address the above comments and introduce
>a IDLE role driver so we can deal with Type-C lane swap.
>
>Please squash them into this patch, if they look OK. Thanks.
>
>cheers,
>-roger
>--
>
>From 228da29ea47d0000f2bab49377fce8f3f0e97b63 Mon Sep 17 00:00:00 2001
>From: Roger Quadros <rogerq@ti.com>
>Date: Thu, 15 Aug 2019 11:11:02 +0300
>Subject: [PATCH 1/2] usb: cdns3: Fix hw based role switch
>
>Signed-off-by: Roger Quadros <rogerq@ti.com>
>---
> drivers/usb/cdns3/core.c | 76 ++++++++++++++++++++++++++--------------
> drivers/usb/cdns3/core.h |  2 ++
> drivers/usb/cdns3/drd.c  |  2 +-
> 3 files changed, 52 insertions(+), 28 deletions(-)
>
>diff --git a/drivers/usb/cdns3/core.c b/drivers/usb/cdns3/core.c
>index b132acca60f1..07f8d8f23930 100644
>--- a/drivers/usb/cdns3/core.c
>+++ b/drivers/usb/cdns3/core.c
>@@ -97,7 +97,7 @@ static void cdns3_exit_roles(struct cdns3 *cdns)
> 	cdns3_drd_exit(cdns);
> }
>
>-enum usb_role cdsn3_real_role_switch_get(struct device *dev);
>+static enum usb_role cdsn3_hw_role_state_machine(struct cdns3 *cdns);
>
> /**
>  * cdns3_core_init_role - initialize role of operation
>@@ -176,7 +176,7 @@ static int cdns3_core_init_role(struct cdns3 *cdns)
> 	if (ret)
> 		goto err;
>
>-	cdns->role = cdsn3_real_role_switch_get(cdns->dev);
>+	cdns->role = cdsn3_hw_role_state_machine(cdns);
>
> 	ret = cdns3_role_start(cdns, cdns->role);
> 	if (ret) {
>@@ -192,15 +192,14 @@ static int cdns3_core_init_role(struct cdns3 *cdns)
> }
>
> /**
>- * cdsn3_real_role_switch_get - get real role of controller based on hardware
>- *   settings.
>- * @dev: Pointer to device structure
>+ * cdsn3_hw_role_state_machine - role switch state machine based on hw events
>  *
>- * Returns role
>+ * @cdns: Pointer to controller structure
>+ *
>+ * Returns next role to be entered based on hw events.
>  */
>-enum usb_role cdsn3_real_role_switch_get(struct device *dev)
>+static enum usb_role cdsn3_hw_role_state_machine(struct cdns3 *cdns)
> {
>-	struct cdns3 *cdns = dev_get_drvdata(dev);
> 	enum usb_role role;
> 	int id, vbus;
>
>@@ -253,46 +252,40 @@ enum usb_role cdsn3_real_role_switch_get(struct device *dev)
> }
>
> /**
>- * cdns3_role_switch_set - work queue handler for role switch
>+ * cdns3_hw_role_switch - switch roles based on HW state
>  *
>- * @dev: pointer to device object
>- * @role - the previous role
>- * Handles below events:
>- * - Role switch for dual-role devices
>- * - USB_ROLE_GADGET <--> USB_ROLE_NONE for peripheral-only devices
>+ * @cdns: controller
>  */
>-static int cdns3_role_switch_set(struct device *dev, enum usb_role role)
>+int cdns3_hw_role_switch(struct cdns3 *cdns)
> {
>-	struct cdns3 *cdns = dev_get_drvdata(dev);
>-	enum usb_role real_role = USB_ROLE_NONE;
>-	enum usb_role current_role;
>+	enum usb_role real_role, current_role;
> 	int ret = 0;
>
> 	/* Check if dr_mode was changed.*/
>+	/* FIXME: why do we need this call? */
> 	ret = cdns3_drd_update_mode(cdns);
> 	if (ret)
> 		return ret;
>
>+	/* FIXME: don't do anything if userspace role switch has override */
> 	pm_runtime_get_sync(cdns->dev);
>
>-	real_role = cdsn3_real_role_switch_get(cdns->dev);
>+	current_role = cdns->role;
>+	real_role = cdsn3_hw_role_state_machine(cdns);
>
> 	/* Do nothing if nothing changed */
>-	if (cdns->role == real_role)
>+	if (current_role == real_role)
> 		goto exit;
>
> 	cdns3_role_stop(cdns);
>
>-	real_role = cdsn3_real_role_switch_get(cdns->dev);
>-
>-	current_role = role;
>-	dev_dbg(cdns->dev, "Switching role");
>+	dev_dbg(cdns->dev, "Switching role %d -> %d", current_role, real_role);
>
> 	ret = cdns3_role_start(cdns, real_role);
> 	if (ret) {
> 		/* Back to current role */
> 		dev_err(cdns->dev, "set %d has failed, back to %d\n",
>-			role, current_role);
>+			real_role, current_role);
> 		ret = cdns3_role_start(cdns, current_role);
> 		if (ret)
> 			dev_err(cdns->dev, "back to %d failed too\n",
>@@ -303,9 +296,38 @@ static int cdns3_role_switch_set(struct device *dev, enum usb_role role)
> 	return ret;
> }
>
>+/**
>+ * cdsn3_role_get - get current role of controller.
>+ *
>+ * @dev: Pointer to device structure
>+ *
>+ * Returns role
>+ */
>+static enum usb_role cdns3_role_get(struct device *dev)
>+{
>+	struct cdns3 *cdns = dev_get_drvdata(dev);
>+
>+	return cdns->role;
>+}
>+
>+/**
>+ * cdns3_role_set - set current role of controller.
>+ *
>+ * @dev: pointer to device object
>+ * @role - the previous role
>+ * Handles below events:
>+ * - Role switch for dual-role devices
>+ * - USB_ROLE_GADGET <--> USB_ROLE_NONE for peripheral-only devices
>+ */
>+static int cdns3_role_set(struct device *dev, enum usb_role role)
>+{
>+	/* FIXME: doing nothing for now */
>+	return -EPERM;
>+}
>+
> static const struct usb_role_switch_desc cdns3_switch_desc = {
>-	.set = cdns3_role_switch_set,
>-	.get = cdsn3_real_role_switch_get,
>+	.set = cdns3_role_set,
>+	.get = cdns3_role_get,
> 	.allow_userspace_control = true,
> };
>
>diff --git a/drivers/usb/cdns3/core.h b/drivers/usb/cdns3/core.h
>index 2a35f025b0a5..e0d23f2934bb 100644
>--- a/drivers/usb/cdns3/core.h
>+++ b/drivers/usb/cdns3/core.h
>@@ -103,4 +103,6 @@ struct cdns3 {
> 	struct usb_role_switch		*role_sw;
> };
>
>+int cdns3_hw_role_switch(struct cdns3 *cdns);
>+
> #endif /* __LINUX_CDNS3_CORE_H */
>diff --git a/drivers/usb/cdns3/drd.c b/drivers/usb/cdns3/drd.c
>index 77f8a1516140..780fc7d59932 100644
>--- a/drivers/usb/cdns3/drd.c
>+++ b/drivers/usb/cdns3/drd.c
>@@ -265,7 +265,7 @@ static irqreturn_t cdns3_drd_thread_irq(int irq, void *data)
> {
> 	struct cdns3 *cdns = data;
>
>-	usb_role_switch_set_role(cdns->role_sw, cdns->role);
>+	cdns3_hw_role_switch(cdns);
>
> 	return IRQ_HANDLED;
> }
>
>
>From 701277afb2c1087d327be5387b239d507f0abf6e Mon Sep 17 00:00:00 2001
>From: Roger Quadros <rogerq@ti.com>
>Date: Thu, 15 Aug 2019 11:39:38 +0300
>Subject: [PATCH 2/2] usb: cdns3: fix type-c lane swap
>
>We need to have a discrete IDLE state so that
>we know type-C cable is disconnected.
>
>On exting IDLE state we can program lane swap
>via a PHY reset.
>
>Signed-off-by: Roger Quadros <rogerq@ti.com>
>---
> drivers/usb/cdns3/core.c   | 49 +++++++++++++++++++++++++++-----------
> drivers/usb/cdns3/gadget.c |  2 ++
> drivers/usb/cdns3/host.c   |  3 +++
> 3 files changed, 40 insertions(+), 14 deletions(-)
>
>diff --git a/drivers/usb/cdns3/core.c b/drivers/usb/cdns3/core.c
>index 07f8d8f23930..3c42ee347836 100644
>--- a/drivers/usb/cdns3/core.c
>+++ b/drivers/usb/cdns3/core.c
>@@ -44,9 +44,6 @@ static int cdns3_role_start(struct cdns3 *cdns, enum usb_role role)
> 	cdns->role = role;
> 	mutex_unlock(&cdns->mutex);
>
>-	if (role == USB_ROLE_NONE)
>-		return 0;
>-
> 	if (!cdns->roles[role])
> 		return -ENXIO;
>
>@@ -54,10 +51,6 @@ static int cdns3_role_start(struct cdns3 *cdns, enum usb_role role)
> 		return 0;
>
> 	mutex_lock(&cdns->mutex);
>-	if (role == USB_ROLE_HOST)
>-		cdns3_drd_switch_host(cdns, 1);
>-	else
>-		cdns3_drd_switch_gadget(cdns, 1);
>
> 	ret = cdns->roles[role]->start(cdns);
> 	if (!ret)
>@@ -74,18 +67,11 @@ static void cdns3_role_stop(struct cdns3 *cdns)
> 	if (WARN_ON(role > USB_ROLE_DEVICE))
> 		return;
>
>-	if (role == USB_ROLE_NONE)
>-		return;
>-
> 	if (cdns->roles[role]->state == CDNS3_ROLE_STATE_INACTIVE)
> 		return;
>
> 	mutex_lock(&cdns->mutex);
> 	cdns->roles[role]->stop(cdns);
>-	if (role == USB_ROLE_HOST)
>-		cdns3_drd_switch_host(cdns, 0);
>-	else
>-		cdns3_drd_switch_gadget(cdns, 0);
>
> 	cdns->roles[role]->state = CDNS3_ROLE_STATE_INACTIVE;
> 	mutex_unlock(&cdns->mutex);
>@@ -99,6 +85,37 @@ static void cdns3_exit_roles(struct cdns3 *cdns)
>
> static enum usb_role cdsn3_hw_role_state_machine(struct cdns3 *cdns);
>
>+static int cdns3_idle_role_start(struct cdns3 *cdns)
>+{
>+	return 0;
>+}
>+
>+static void cdns3_idle_role_stop(struct cdns3 *cdns)
>+{
>+	/* Program Lane swap and bring PHY out of RESET */
>+	phy_reset(cdns->usb3_phy);
>+}
>+
>+static int cdns3_idle_init(struct cdns3 *cdns)
>+{
>+	struct cdns3_role_driver *rdrv;
>+
>+	rdrv = devm_kzalloc(cdns->dev, sizeof(*rdrv), GFP_KERNEL);
>+	if (!rdrv)
>+		return -ENOMEM;
>+
>+	rdrv->start = cdns3_idle_role_start;
>+	rdrv->stop = cdns3_idle_role_stop;
>+	rdrv->state = CDNS3_ROLE_STATE_INACTIVE;
>+	rdrv->suspend = NULL;
>+	rdrv->resume = NULL;
>+	rdrv->name = "idle";
>+
>+	cdns->roles[USB_ROLE_NONE] = rdrv;
>+
>+	return 0;
>+}
>+
> /**
>  * cdns3_core_init_role - initialize role of operation
>  * @cdns: Pointer to cdns3 structure
>@@ -136,6 +153,10 @@ static int cdns3_core_init_role(struct cdns3 *cdns)
> 	 */
> 	best_dr_mode = cdns->dr_mode;
>
>+	ret = cdns3_idle_init(cdns);
>+	if (ret)
>+		return ret;
>+
> 	if (dr_mode == USB_DR_MODE_OTG) {
> 		best_dr_mode = cdns->dr_mode;
> 	} else if (cdns->dr_mode == USB_DR_MODE_OTG) {
>diff --git a/drivers/usb/cdns3/gadget.c b/drivers/usb/cdns3/gadget.c
>index a42e832b3c6a..2ac2eba284c7 100644
>--- a/drivers/usb/cdns3/gadget.c
>+++ b/drivers/usb/cdns3/gadget.c
>@@ -2475,6 +2475,7 @@ void cdns3_gadget_exit(struct cdns3 *cdns)
> 	kfree(priv_dev->zlp_buf);
> 	kfree(priv_dev);
> 	cdns->gadget_dev = NULL;
>+	cdns3_drd_switch_gadget(cdns, 0);
> }
>
> static int cdns3_gadget_start(struct cdns3 *cdns)
>@@ -2594,6 +2595,7 @@ static int __cdns3_gadget_init(struct cdns3 *cdns)
> 	struct cdns3_device *priv_dev;
> 	int ret = 0;
>
>+	cdns3_drd_switch_gadget(cdns, 1);
> 	pm_runtime_get_sync(cdns->dev);
>
> 	ret = cdns3_gadget_start(cdns);
>diff --git a/drivers/usb/cdns3/host.c b/drivers/usb/cdns3/host.c
>index a7629ab2c20c..2733a8f71fcd 100644
>--- a/drivers/usb/cdns3/host.c
>+++ b/drivers/usb/cdns3/host.c
>@@ -18,6 +18,8 @@ static int __cdns3_host_init(struct cdns3 *cdns)
> 	struct platform_device *xhci;
> 	int ret;
>
>+	cdns3_drd_switch_host(cdns, 1);
>+
> 	xhci = platform_device_alloc("xhci-hcd", PLATFORM_DEVID_AUTO);
> 	if (!xhci) {
> 		dev_err(cdns->dev, "couldn't allocate xHCI device\n");
>@@ -50,6 +52,7 @@ static void cdns3_host_exit(struct cdns3 *cdns)
> {
> 	platform_device_unregister(cdns->host_dev);
> 	cdns->host_dev = NULL;
>+	cdns3_drd_switch_host(cdns, 0);
> }
>
> int cdns3_host_init(struct cdns3 *cdns)
>
--
Cheers,
pawell