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Date: Fri, 20 Nov 2015 10:45:39 +0100
From: Marek Szyprowski <m.szyprowski@...sung.com>
To: Peter Chen <peter.chen@...escale.com>
Cc: linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
Ruslan Bilovol <ruslan.bilovol@...il.com>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Subject: Re: [PATCH v6 4/4] usb: gadget: udc-core: independent registration of
gadgets and gadget drivers
Hello,
On 2015-11-20 10:26, Peter Chen wrote:
> On Fri, Nov 20, 2015 at 09:54:12AM +0100, Marek Szyprowski wrote:
>> From: Ruslan Bilovol <ruslan.bilovol@...il.com>
>>
>> Change behavior during registration of gadgets and
>> gadget drivers in udc-core. Instead of previous
>> approach when for successful probe of usb gadget driver
>> at least one usb gadget should be already registered
>> use another one where gadget drivers and gadgets
>> can be registered in udc-core independently.
>>
>> Independent registration of gadgets and gadget drivers
>> is useful for built-in into kernel gadget and gadget
>> driver case - because it's possible that gadget is
>> really probed only on late_init stage (due to deferred
>> probe) whereas gadget driver's probe is silently failed
>> on module_init stage due to no any UDC added.
>>
>> Also it is useful for modules case - now there is no
>> difference what module to insert first: gadget module
>> or gadget driver one.
>>
>> Tested-by: Maxime Ripard <maxime.ripard@...e-electrons.com>
>> Signed-off-by: Ruslan Bilovol <ruslan.bilovol@...il.com>
>> [simplified code as requested by Alan Stern and Felipe Balbi]
>> Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
>> ---
>> drivers/usb/gadget/udc/udc-core.c | 43 +++++++++++++++++++++++++++++++--------
>> include/linux/usb/gadget.h | 2 ++
>> 2 files changed, 37 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/usb/gadget/udc/udc-core.c b/drivers/usb/gadget/udc/udc-core.c
>> index f76ebc8..461b311 100644
>> --- a/drivers/usb/gadget/udc/udc-core.c
>> +++ b/drivers/usb/gadget/udc/udc-core.c
>> @@ -51,8 +51,12 @@ struct usb_udc {
>>
>> static struct class *udc_class;
>> static LIST_HEAD(udc_list);
>> +static LIST_HEAD(gadget_driver_pending_list);
>> static DEFINE_MUTEX(udc_lock);
>>
>> +static int udc_bind_to_driver(struct usb_udc *udc,
>> + struct usb_gadget_driver *driver);
>> +
>> /* ------------------------------------------------------------------------- */
>>
>> #ifdef CONFIG_HAS_DMA
>> @@ -356,6 +360,7 @@ int usb_add_gadget_udc_release(struct device *parent, struct usb_gadget *gadget,
>> void (*release)(struct device *dev))
>> {
>> struct usb_udc *udc;
>> + struct usb_gadget_driver *driver;
>> int ret = -ENOMEM;
>>
>> udc = kzalloc(sizeof(*udc), GFP_KERNEL);
>> @@ -403,6 +408,18 @@ int usb_add_gadget_udc_release(struct device *parent, struct usb_gadget *gadget,
>> usb_gadget_set_state(gadget, USB_STATE_NOTATTACHED);
>> udc->vbus = true;
>>
>> + /* pick up one of pending gadget drivers */
>> + list_for_each_entry(driver, &gadget_driver_pending_list, pending) {
>> + if (!driver->udc_name || strcmp(driver->udc_name,
>> + dev_name(&udc->dev)) == 0) {
>> + ret = udc_bind_to_driver(udc, driver);
>> + if (ret)
>> + goto err4;
>> + list_del(&driver->pending);
>> + break;
>> + }
>> + }
>> +
>> mutex_unlock(&udc_lock);
>>
>> return 0;
>> @@ -475,9 +492,16 @@ void usb_del_gadget_udc(struct usb_gadget *gadget)
>> list_del(&udc->list);
>> mutex_unlock(&udc_lock);
>>
>> - if (udc->driver)
>> + if (udc->driver) {
>> + struct usb_gadget_driver *driver = udc->driver;
>> +
>> usb_gadget_remove_driver(udc);
>>
>> + mutex_lock(&udc_lock);
>> + list_add(&driver->pending, &gadget_driver_pending_list);
>> + mutex_unlock(&udc_lock);
>> + }
>> +
>> kobject_uevent(&udc->dev.kobj, KOBJ_REMOVE);
>> flush_work(&gadget->work);
>> device_unregister(&udc->dev);
>> @@ -535,11 +559,7 @@ int usb_gadget_probe_driver(struct usb_gadget_driver *driver)
>> if (!ret)
>> break;
>> }
>> - if (ret)
>> - ret = -ENODEV;
>> - else if (udc->driver)
>> - ret = -EBUSY;
>> - else
>> + if (!ret && !udc->driver)
>> goto found;
>> } else {
>> list_for_each_entry(udc, &udc_list, list) {
>> @@ -549,9 +569,12 @@ int usb_gadget_probe_driver(struct usb_gadget_driver *driver)
>> }
>> }
>>
>> - pr_debug("couldn't find an available UDC\n");
>> + list_add_tail(&driver->pending, &gadget_driver_pending_list);
>> + pr_info("udc-core: couldn't find an available UDC "
>> + "- added [%s] to list of pending drivers\n",
>> + driver->function);
>> mutex_unlock(&udc_lock);
>> - return ret;
>> + return 0;
>> found:
>> ret = udc_bind_to_driver(udc, driver);
>> mutex_unlock(&udc_lock);
>> @@ -577,6 +600,10 @@ int usb_gadget_unregister_driver(struct usb_gadget_driver *driver)
>> break;
>> }
>>
>> + if (ret) {
>> + list_del(&driver->pending);
>> + ret = 0;
>> + }
>> mutex_unlock(&udc_lock);
>> return ret;
>> }
>> diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
>> index e11f5a2..a3436bf 100644
>> --- a/include/linux/usb/gadget.h
>> +++ b/include/linux/usb/gadget.h
>> @@ -1014,6 +1014,7 @@ static inline int usb_gadget_activate(struct usb_gadget *gadget)
>> * @driver: Driver model state for this driver.
>> * @udc_name: A name of UDC this driver should be bound to. If udc_name is NULL,
>> * this driver will be bound to any available UDC.
>> + * @pending: UDC core private data used for deferred probe of this driver.
>> *
>> * Devices are disabled till a gadget driver successfully bind()s, which
>> * means the driver will handle setup() requests needed to enumerate (and
>> @@ -1076,6 +1077,7 @@ struct usb_gadget_driver {
>> struct device_driver driver;
>>
>> char *udc_name;
>> + struct list_head pending;
>> };
>>
>>
> And it seems can't apply for felipe's testing/next which I just rebased
> on it.
I really have no idea why it fails for You. The patchset applies
correctly on both
Felipe's 'next' and 'testing/next' branches from today.
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
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