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

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Date:   Mon, 12 Aug 2019 09:43:31 +0000
From:   Pawel Laszczak <pawell@...ence.com>
To:     Roger Quadros <rogerq@...com>,
        "felipe.balbi@...ux.intel.com" <felipe.balbi@...ux.intel.com>
CC:     "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "jbergsagel@...com" <jbergsagel@...com>,
        "nsekhar@...com" <nsekhar@...com>, "nm@...com" <nm@...com>,
        Suresh Punnoose <sureshp@...ence.com>,
        Jayshri Dajiram Pawar <jpawar@...ence.com>,
        Rahul Kumar <kurahul@...ence.com>,
        Anil Joy Varughese <aniljoy@...ence.com>,
        "heikki.krogerus@...ux.intel.com" <heikki.krogerus@...ux.intel.com>
Subject: RE: [PATCH v10 5/6] usb:cdns3 Add Cadence USB3 DRD Driver

Hi,

>
>On 11/08/2019 14:59, Pawel Laszczak wrote:
>> 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@...ence.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
>>>>
>>>> diff --git a/drivers/usb/Kconfig b/drivers/usb/Kconfig
>>>> index e4b27413f528..c2e78882f8c2 100644
>>>> --- a/drivers/usb/Kconfig
>>>> +++ b/drivers/usb/Kconfig
>>>> @@ -113,6 +113,8 @@ source "drivers/usb/usbip/Kconfig"
>>>>
>>>>  endif
>>>>

<snip>

>>>> +	real_role = cdsn3_real_role_switch_get(cdns->dev);
>>>> +
>>>> +	current_role = role;
>>>> +	dev_dbg(cdns->dev, "Switching 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);
>>>> +		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;
>>>> +}
>>>> +
>>>> +static const struct usb_role_switch_desc cdns3_switch_desc = {
>>>> +	.set = cdns3_role_switch_set,
>>>> +	.get = cdsn3_real_role_switch_get,
>>>> +	.allow_userspace_control = true,
>>>
>>> how does user initiated cdns3_role_switch_set() via sysfs co-exist with role
>>> changes done by hardware events. e.g. ID/VBUS?
>>>
>>
>> Do you expect any issues whit this,  have you seen any problem with this
>> on your  platform ?
>>
>> I assume that it should work in this way:
>> 1. user change role by sysfs
>> 2. Driver change the role according with user request.
>> 3. If we receive correct ID/VBUS then role should not be changed
>>     because new role is the same as current set in point 2.
>>
>
>I have not tested this series yet.
>My understanding is that if user sets role to "host" or "device" then it should
>remain in that role irrespective of ID/VBUS. Once user sets it to "none" then
>port should set role based on ID/VBUS.

According with your understanding it works the same way as by debugfs. 
Now I have no doubts to remove debugfs.c file :)

>
>>
>>>> +};
>>>> +
>>>> +/**
>>>> + * cdns3_probe - probe for cdns3 core device
>>>> + * @pdev: Pointer to cdns3 core platform device
>>>> + *
>>>> + * Returns 0 on success otherwise negative errno
>>>> + */
>>>> +static int cdns3_probe(struct platform_device *pdev)

<snip>

>>>> + * 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);
>>>
>>> How to ensure that HW events don't step over user chosen role?
>>
>> I need to think about this and find out how to test it and eventually force
>> such cases.
>>
>> But I assume that after attaching/detaching plug the user chosen role can
>> be forgotten.
>>
>
>No. Only when user sets role to none then role should be based on HW.

Ok, I will try to test it in next week.

>>>
>
><snip>

Cheers,
Pawell