Re: [PATCH v4 5/6] usb:cdns3 Add Cadence USB3 DRD Driver

[Roger Quadros <rogerq@ti.com>]

On 07/03/2019 07:37, Pawel Laszczak wrote:
> Hi,
> 
>> Pawel,
>>
>> On 14/02/2019 21:45, Pawel Laszczak wrote:
>>> This patch introduce new Cadence USBSS DRD driver to linux kernel.
>>>
>>> The Cadence USBSS DRD Driver is a highly configurable IP Core whichi
>>> can be instantiated as Dual-Role Device (DRD), Peripheral Only and
>>> Host Only (XHCI)configurations.
>>>
>>> The current driver has been validated with FPGA burned. We have support
>>> for PCIe bus, which is used on FPGA prototyping.
>>>
>>> The host side of USBSS-DRD controller is compliance 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          |   44 +
>>>  drivers/usb/cdns3/Makefile         |   14 +
>>>  drivers/usb/cdns3/cdns3-pci-wrap.c |  155 +++
>>>  drivers/usb/cdns3/core.c           |  403 ++++++
>>>  drivers/usb/cdns3/core.h           |  116 ++
>>>  drivers/usb/cdns3/debug.h          |  168 +++
>>>  drivers/usb/cdns3/debugfs.c        |  164 +++
>>>  drivers/usb/cdns3/drd.c            |  365 +++++
>>>  drivers/usb/cdns3/drd.h            |  162 +++
>>>  drivers/usb/cdns3/ep0.c            |  907 +++++++++++++
>>>  drivers/usb/cdns3/gadget-export.h  |   28 +
>>>  drivers/usb/cdns3/gadget.c         | 2003 ++++++++++++++++++++++++++++
>>>  drivers/usb/cdns3/gadget.h         | 1207 +++++++++++++++++
>>>  drivers/usb/cdns3/host-export.h    |   28 +
>>>  drivers/usb/cdns3/host.c           |   72 +
>>>  drivers/usb/cdns3/trace.c          |   23 +
>>>  drivers/usb/cdns3/trace.h          |  404 ++++++
>>>  19 files changed, 6267 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
>>>
>>> diff --git a/drivers/usb/Kconfig b/drivers/usb/Kconfig
>>> index 987fc5ba6321..5f9334019d04 100644
>>> --- a/drivers/usb/Kconfig
>>> +++ b/drivers/usb/Kconfig
>>> @@ -112,6 +112,8 @@ source "drivers/usb/usbip/Kconfig"
>>>
>>>  endif
>>>
>>> +source "drivers/usb/cdns3/Kconfig"
>>> +
>>>  source "drivers/usb/mtu3/Kconfig"
>>>
>>>  source "drivers/usb/musb/Kconfig"
>>> diff --git a/drivers/usb/Makefile b/drivers/usb/Makefile
>>> index 7d1b8c82b208..ab125b966cac 100644
>>> --- a/drivers/usb/Makefile
>>> +++ b/drivers/usb/Makefile
>>> @@ -12,6 +12,8 @@ obj-$(CONFIG_USB_DWC3)		+= dwc3/
>>>  obj-$(CONFIG_USB_DWC2)		+= dwc2/
>>>  obj-$(CONFIG_USB_ISP1760)	+= isp1760/
>>>
>>> +obj-$(CONFIG_USB_CDNS3)		+= cdns3/
>>> +
>>>  obj-$(CONFIG_USB_MON)		+= mon/
>>>  obj-$(CONFIG_USB_MTU3)		+= mtu3/
>>>
>>> diff --git a/drivers/usb/cdns3/Kconfig b/drivers/usb/cdns3/Kconfig
>>> new file mode 100644
>>> index 000000000000..27cb3d8dbe3d
>>> --- /dev/null
>>> +++ b/drivers/usb/cdns3/Kconfig
>>> @@ -0,0 +1,44 @@
>>> +config USB_CDNS3
>>> +	tristate "Cadence USB3 Dual-Role Controller"
>>> +	depends on USB_SUPPORT && (USB || USB_GADGET) && HAS_DMA
>>> +	help
>>> +	  Say Y here if your system has a cadence USB3 dual-role controller.
>>> +	  It supports: dual-role switch, Host-only, and Peripheral-only.
>>> +
>>> +	  If you choose to build this driver is a dynamically linked
>>> +	  as module, the module will be called cdns3.ko.
>>> +
>>> +if USB_CDNS3
>>> +
>>> +config USB_CDNS3_GADGET
>>> +        bool "Cadence USB3 device controller"
>>> +        depends on USB_GADGET
>>> +        help
>>> +          Say Y here to enable device controller functionality of the
>>> +          cadence USBSS-DEV driver.
>>
>> "Cadence" ?
>>
>>> +
>>> +          This controller supports FF, HS and SS mode. It doesn't support
>>> +          LS and SSP mode.
>>> +
>>> +config USB_CDNS3_HOST
>>> +        bool "Cadence USB3 host controller"
>>> +        depends on USB_XHCI_HCD
>>> +        help
>>> +          Say Y here to enable host controller functionality of the
>>> +          cadence driver.
>>> +
>>> +          Host controller is compliant with XHCI so it will use
>>> +          standard XHCI driver.
>>> +
>>> +config USB_CDNS3_PCI_WRAP
>>> +	tristate "Cadence USB3 support on PCIe-based platforms"
>>> +	depends on USB_PCI && ACPI
>>> +	default USB_CDNS3
>>> +	help
>>> +	  If you're using the USBSS Core IP with a PCIe, please say
>>> +	  'Y' or 'M' here.
>>> +
>>> +	  If you choose to build this driver as module it will
>>> +	  be dynamically linked and module will be called cdns3-pci.ko
>>> +
>>> +endif
>>> diff --git a/drivers/usb/cdns3/Makefile b/drivers/usb/cdns3/Makefile
>>> new file mode 100644
>>> index 000000000000..8f9438593375
>>> --- /dev/null
>>> +++ b/drivers/usb/cdns3/Makefile
>>> @@ -0,0 +1,14 @@
>>> +# SPDX-License-Identifier: GPL-2.0
>>> +# define_trace.h needs to know how to find our header
>>> +CFLAGS_trace.o				:= -I$(src)
>>> +
>>> +cdns3-y					:= core.o drd.o trace.o
>>> +
>>> +obj-$(CONFIG_USB_CDNS3)			+= cdns3.o
>>> +ifneq ($(CONFIG_DEBUG_FS),)
>>> +	cdns3-y				+= debugfs.o
>>> +endif
>>> +
>>> +cdns3-$(CONFIG_USB_CDNS3_GADGET)	+= gadget.o ep0.o
>>> +cdns3-$(CONFIG_USB_CDNS3_HOST)		+= host.o
>>> +obj-$(CONFIG_USB_CDNS3_PCI_WRAP)	+= cdns3-pci-wrap.o
>>> diff --git a/drivers/usb/cdns3/cdns3-pci-wrap.c b/drivers/usb/cdns3/cdns3-pci-wrap.c
>>> new file mode 100644
>>> index 000000000000..d0b2d3d9b983
>>> --- /dev/null
>>> +++ b/drivers/usb/cdns3/cdns3-pci-wrap.c
>>> @@ -0,0 +1,155 @@
>>> +// SPDX-License-Identifier: GPL-2.0
>>> +/*
>>> + * Cadence USBSS PCI Glue driver
>>> + *
>>> + * Copyright (C) 2018 Cadence.
>>
>> 2018-2019?
>>
>>> + *
>>> + * Author: Pawel Laszczak <pawell@cadence.com>
>>> + */
>>> +
>>> +#include <linux/kernel.h>
>>> +#include <linux/module.h>
>>> +#include <linux/pci.h>
>>> +#include <linux/platform_device.h>
>>> +#include <linux/dma-mapping.h>
>>> +#include <linux/slab.h>
>>> +
>>> +struct cdns3_wrap {
>>> +	struct platform_device *plat_dev;
>>> +	struct pci_dev *hg_dev;
>>> +	struct resource dev_res[4];
>>> +};
>>> +
>>> +struct cdns3_wrap wrap;
>>> +
>>> +#define RES_IRQ_ID		0
>>> +#define RES_HOST_ID		1
>>> +#define RES_DEV_ID		2
>>> +#define RES_DRD_ID		3
>>> +
>>> +#define PCI_BAR_HOST		0
>>> +#define PCI_BAR_DEV		2
>>> +#define PCI_BAR_OTG		4
>>> +
>>> +#define PCI_DEV_FN_HOST_DEVICE	0
>>> +#define PCI_DEV_FN_OTG		1
>>> +
>>> +#define PCI_DRIVER_NAME		"cdns3-pci-usbss"
>>> +#define PLAT_DRIVER_NAME	"cdns-usb3"
>>> +
>>> +#define CDNS_VENDOR_ID 0x17cd
>>> +#define CDNS_DEVICE_ID 0x0100
>>> +
>>> +/**
>>> + * cdns3_pci_probe - Probe function for Cadence USB wrapper driver
>>> + * @pdev: platform device object
>>> + * @id: pci device id
>>> + *
>>> + * Returns 0 on success otherwise negative errno
>>> + */
>>> +static int cdns3_pci_probe(struct pci_dev *pdev,
>>> +			   const struct pci_device_id *id)
>>> +{
>>> +	struct platform_device_info plat_info;
>>> +	struct cdns3_wrap *wrap;
>>> +	struct resource *res;
>>> +	int err;
>>> +
>>> +	/*
>>> +	 * for GADGET/HOST PCI (devfn) function number is 0,
>>> +	 * for OTG PCI (devfn) function number is 1
>>> +	 */
>>> +	if (!id || pdev->devfn != PCI_DEV_FN_HOST_DEVICE)
>>> +		return -EINVAL;
>>> +
>>> +	err = pcim_enable_device(pdev);
>>> +	if (err) {
>>> +		dev_err(&pdev->dev, "Enabling PCI device has failed %d\n", err);
>>> +		return err;
>>> +	}
>>> +
>>> +	pci_set_master(pdev);
>>> +	wrap = devm_kzalloc(&pdev->dev, sizeof(*wrap), GFP_KERNEL);
>>> +	if (!wrap) {
>>> +		dev_err(&pdev->dev, "Failed to allocate memory\n");
>>> +		return -ENOMEM;
>>> +	}
>>> +
>>> +	/* function 0: host(BAR_0) + device(BAR_1) + otg(BAR_2)). */
>>> +	memset(wrap->dev_res, 0x00,
>>> +	       sizeof(struct resource) * ARRAY_SIZE(wrap->dev_res));
>>> +	dev_dbg(&pdev->dev, "Initialize Device resources\n");
>>> +	res = wrap->dev_res;
>>> +
>>> +	res[RES_DEV_ID].start = pci_resource_start(pdev, PCI_BAR_DEV);
>>> +	res[RES_DEV_ID].end =   pci_resource_end(pdev, PCI_BAR_DEV);
>>> +	res[RES_DEV_ID].name = "dev";
>>> +	res[RES_DEV_ID].flags = IORESOURCE_MEM;
>>> +	dev_dbg(&pdev->dev, "USBSS-DEV physical base addr: %pa\n",
>>> +		&res[RES_DEV_ID].start);
>>> +
>>> +	res[RES_HOST_ID].start = pci_resource_start(pdev, PCI_BAR_HOST);
>>> +	res[RES_HOST_ID].end = pci_resource_end(pdev, PCI_BAR_HOST);
>>> +	res[RES_HOST_ID].name = "xhci";
>>> +	res[RES_HOST_ID].flags = IORESOURCE_MEM;
>>> +	dev_dbg(&pdev->dev, "USBSS-XHCI physical base addr: %pa\n",
>>> +		&res[RES_HOST_ID].start);
>>> +
>>> +	res[RES_DRD_ID].start = pci_resource_start(pdev, PCI_BAR_OTG);
>>> +	res[RES_DRD_ID].end =   pci_resource_end(pdev, PCI_BAR_OTG);
>>> +	res[RES_DRD_ID].name = "otg";
>>> +	res[RES_DRD_ID].flags = IORESOURCE_MEM;
>>> +	dev_dbg(&pdev->dev, "USBSS-DRD physical base addr: %pa\n",
>>> +		&res[RES_DRD_ID].start);
>>> +
>>> +	/* Interrupt common for both device and XHCI */
>>> +	wrap->dev_res[RES_IRQ_ID].start = pdev->irq;
>>> +	wrap->dev_res[RES_IRQ_ID].name = "cdns3-irq";
>>> +	wrap->dev_res[RES_IRQ_ID].flags = IORESOURCE_IRQ;
>>> +
>>> +	/* set up platform device info */
>>> +	memset(&plat_info, 0, sizeof(plat_info));
>>> +	plat_info.parent = &pdev->dev;
>>> +	plat_info.fwnode = pdev->dev.fwnode;
>>> +	plat_info.name = PLAT_DRIVER_NAME;
>>> +	plat_info.id = pdev->devfn;
>>> +	plat_info.res = wrap->dev_res;
>>> +	plat_info.num_res = ARRAY_SIZE(wrap->dev_res);
>>> +	plat_info.dma_mask = pdev->dma_mask;
>>> +
>>> +	/* register platform device */
>>> +	wrap->plat_dev = platform_device_register_full(&plat_info);
>>> +	if (IS_ERR(wrap->plat_dev))
>>> +		return PTR_ERR(wrap->plat_dev);
>>> +
>>> +	pci_set_drvdata(pdev, wrap);
>>> +
>>> +	return err;
>>> +}
>>> +
>>> +void cdns3_pci_remove(struct pci_dev *pdev)
>>> +{
>>> +	struct cdns3_wrap *wrap = (struct cdns3_wrap *)pci_get_drvdata(pdev);
>>> +
>>> +	platform_device_unregister(wrap->plat_dev);
>>> +}
>>> +
>>> +static const struct pci_device_id cdns3_pci_ids[] = {
>>> +	{ PCI_DEVICE(CDNS_VENDOR_ID, CDNS_DEVICE_ID), },
>>> +	{ 0, }
>>> +};
>>> +
>>> +static struct pci_driver cdns3_pci_driver = {
>>> +	.name = PCI_DRIVER_NAME,
>>> +	.id_table = cdns3_pci_ids,
>>> +	.probe = cdns3_pci_probe,
>>> +	.remove = cdns3_pci_remove,
>>> +};
>>> +
>>> +module_pci_driver(cdns3_pci_driver);
>>> +MODULE_DEVICE_TABLE(pci, cdns3_pci_ids);
>>> +
>>> +MODULE_AUTHOR("Pawel Laszczak <pawell@cadence.com>");
>>> +MODULE_LICENSE("GPL v2");
>>> +MODULE_DESCRIPTION("Cadence USBSS PCI wrapperr");
>>> +
>>> diff --git a/drivers/usb/cdns3/core.c b/drivers/usb/cdns3/core.c
>>> new file mode 100644
>>> index 000000000000..aa2f63241dab
>>> --- /dev/null
>>> +++ b/drivers/usb/cdns3/core.c
>>> @@ -0,0 +1,403 @@
>>> +// SPDX-License-Identifier: GPL-2.0
>>> +/*
>>> + * Cadence USBSS DRD Driver.
>>> + *
>>> + * Copyright (C) 2018 Cadence.
>>> + * Copyright (C) 2017-2018 NXP
>>> + *
>>> + * Author: Peter Chen <peter.chen@nxp.com>
>>> + *         Pawel Laszczak <pawell@cadence.com>
>>> + */
>>> +
>>> +#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->role >= CDNS3_ROLE_END || !cdns->roles[cdns->role]);
>>> +	return cdns->roles[cdns->role];
>>> +}
>>> +
>>> +static int cdns3_role_start(struct cdns3 *cdns, enum cdns3_roles role)
>>> +{
>>> +	int ret;
>>> +
>>> +	if (WARN_ON(role >= CDNS3_ROLE_END))
>>> +		return 0;
>>> +
>>> +	if (!cdns->roles[role])
>>> +		return -ENXIO;
>>> +
>>> +	if (cdns->roles[role]->state == CDNS3_ROLE_STATE_ACTIVE)
>>> +		return 0;
>>> +
>>> +	mutex_lock(&cdns->mutex);
>>> +	cdns->role = role;
>>> +	ret = cdns->roles[role]->start(cdns);
>>> +	if (!ret)
>>> +		cdns->roles[role]->state = CDNS3_ROLE_STATE_ACTIVE;
>>> +	mutex_unlock(&cdns->mutex);
>>> +	return ret;
>>> +}
>>> +
>>> +void cdns3_role_stop(struct cdns3 *cdns)
>>> +{
>>> +	enum cdns3_roles role = cdns->role;
>>> +
>>> +	if (role >= CDNS3_ROLE_END) {
>>> +		WARN_ON(role > CDNS3_ROLE_END);
>>> +		return;
>>> +	}
>>> +
>>> +	if (cdns->roles[role]->state == CDNS3_ROLE_STATE_INACTIVE)
>>> +		return;
>>> +
>>> +	mutex_lock(&cdns->mutex);
>>> +	cdns->roles[role]->stop(cdns);
>>> +	cdns->roles[role]->state = CDNS3_ROLE_STATE_INACTIVE;
>>> +	mutex_unlock(&cdns->mutex);
>>> +}
>>> +
>>> +/*
>>> + * cdns->role gets from cdns3_get_initial_role, and this API tells role at the
>>> + * runtime.
>>> + * If both roles are supported, the role is selected based on vbus/id.
>>> + * It could be read from OTG register or external connector.
>>> + * If only single role is supported, only one role structure
>>> + * is allocated, cdns->roles[CDNS3_ROLE_HOST] or cdns->roles[CDNS3_ROLE_GADGET].
>>> + */
>>> +static enum cdns3_roles cdns3_get_initial_role(struct cdns3 *cdns)
>>> +{
>>> +	if (cdns->roles[CDNS3_ROLE_HOST] && cdns->roles[CDNS3_ROLE_GADGET]) {
>>> +		if (cdns3_is_host(cdns))
>>> +			return CDNS3_ROLE_HOST;
>>> +		if (cdns3_is_device(cdns))
>>> +			return CDNS3_ROLE_GADGET;
>>> +	}
>>> +	return cdns->roles[CDNS3_ROLE_HOST]
>>> +		? CDNS3_ROLE_HOST
>>> +		: CDNS3_ROLE_GADGET;
>>> +}
>>> +
>>> +static void cdns3_exit_roles(struct cdns3 *cdns)
>>> +{
>>> +	cdns3_role_stop(cdns);
>>> +	cdns3_drd_exit(cdns);
>>> +}
>>> +
>>> +/**
>>> + * 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 = CDNS3_ROLE_END;
>>> +
>>> +	/*
>>> +	 * If driver can't read mode by means of usb_get_dr_mdoe function then
>>
>> s/mdoe/mode
>>
>>> +	 * 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;
>>> +	}
>>> +
>>> +	best_dr_mode = USB_DR_MODE_OTG;
>>
>> Might be worth mentioning that cdns->dr_mode is strap configuration
>> at this point.
> I added such information. It could help in understanding code.
>>
>> What exactly are we trying to do here?
>> My guess is that choosen dr_mode can be equal to or subset of strap configuration?
>>
> We have three possibility regarding dr_mode:
> 1. It can be read from strap bits
> 2. we have kernel configuration 
> 3. we can read it from dts. 
> 
> I assume that driver should select dr_mode considering these three settings. 
> 
>> Does this work?
> 
>>
>> 	if (cdns->dr_mode != USB_DR_MODE_OTG) {
>> 		if (cdns->dr_mode != dr_mode) {
>> 			dev_err(dev, "Incorrect dr_mode configuration: strap %d: requested %d\n",
>> 				cdns->dr_mode, dr_mode);
>> 		}
>> 	}
>>
>> At this point, dr_mode contains the mode we need to use.
> 
> I don't understand. Do you want to replace below block with above condition ?

Yes.

> If yes, what with case cdns->dr_mode =  USB_DR_MODE_OTG (strap configuration)
> and dr_mode = USB_DR_MODE_HOST (Kernel configuration). 
> I think that in this case driver should limit cdns->dr_mode to USB_DR_MODE_HOST 
> because gadget driver is disabled.  

You are right. It won't work there.

> Of course we can also consider such case as incorrect kernel configuration.

No. It is correct.
I was thinking if we can get rid of best_dr_mode variable entirely, but nevermind.

> 
>>
>>> +
>>> +	if (dr_mode == USB_DR_MODE_OTG) {
>>> +		best_dr_mode = cdns->dr_mode;

I think this is wrong. Why do you want to limit to strap configuration when
user wants it to be in OTG?

>>> +	} 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;
>>> +	/*
>>> +	 * dr_mode could be change so DRD must update controller
>>
>> "desired_dr_mode might have changed so we need to update the controller configuration"?
> 
> Sounds better. 
> 

<snip>

-- 
cheers,
-roger

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