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

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Hi Roger,

>>>
>>> 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@xxxxxxxxxxx>
>>>> ---
>>>>  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@xxxxxxxxxxx>
>>>> + */
>>>> +
>>>> +#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@xxxxxxxxxxx>");
>>>> +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@xxxxxxx>
>>>> + *         Pawel Laszczak <pawell@xxxxxxxxxxx>
>>>> + */
>>>> +
>>>> +#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?

The code should look like: 
	best_dr_mode = cdns->dr_mode;   //this line was incorrect

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

In cdns3_drd_init driver set cdns->dr_mode according to STRAP configuration.
In cdns3_core_init_role driver  set dr_mode according to Kernel configuration.

Then if this two setting is not compatible with each other then driver tray to choose 
the best solution.

Let's assume:
  cdns->dr_mode == USB_DR_MODE_HOST  - based on STRAP.
  dr_mode == USB_DR_MODE_OTG - based on kernel configuration. 

In this case we should consider only USB_DR_MODE_HOST because 
CONFIG_USB_CDNS3_GADGET is not set so we don't have compiled
part of driver responsible for device side. 

>
>>>> +	} 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,
Pawel




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