linux-kernel - Re: [PATCH 2/2] gadget: Support for the usb charger framework

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Date:	Fri, 7 Aug 2015 16:46:31 +0800
From:	Baolin Wang <baolin.wang@...aro.org>
To:	Peter Chen <peter.chen@...escale.com>
Cc:	Felipe Balbi <balbi@...com>, Mark Brown <broonie@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Greg KH <gregkh@...uxfoundation.org>, sojka@...ica.cz,
	Alan Stern <stern@...land.harvard.edu>, andreas@...sler.com,
	linux-usb@...r.kernel.org,
	device-mainlining@...ts.linuxfoundation.org
Subject: Re: [PATCH 2/2] gadget: Support for the usb charger framework

On 7 August 2015 at 13:45, Peter Chen <peter.chen@...escale.com> wrote:
> On Thu, Aug 06, 2015 at 03:03:49PM +0800, Baolin Wang wrote:
>> The usb charger framework is based on usb gadget, and each usb gadget
>> can be one usb charger to set the current limitation.
>>
>> This patch adds a notifier mechanism for usb charger to report to usb
>> charger when the usb gadget state is changed.
>>
>> Also we introduce a callback 'get_charger_type' which will implemented
>> by user for usb gadget operations to get the usb charger type.
>>
>> Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
>> ---
>>  drivers/usb/gadget/udc/udc-core.c |   41 +++++++++++++++++++++++++++++++++++++
>>  include/linux/usb/gadget.h        |   20 ++++++++++++++++++
>>  2 files changed, 61 insertions(+)
>>
>> diff --git a/drivers/usb/gadget/udc/udc-core.c b/drivers/usb/gadget/udc/udc-core.c
>> index d69c355..d5368088 100644
>> --- a/drivers/usb/gadget/udc/udc-core.c
>> +++ b/drivers/usb/gadget/udc/udc-core.c
>> @@ -28,6 +28,7 @@
>>  #include <linux/usb/ch9.h>
>>  #include <linux/usb/gadget.h>
>>  #include <linux/usb.h>
>> +#include <linux/usb/usb_charger.h>
>>
>>  /**
>>   * struct usb_udc - describes one usb device controller
>> @@ -127,12 +128,45 @@ void usb_gadget_giveback_request(struct usb_ep *ep,
>>  }
>>  EXPORT_SYMBOL_GPL(usb_gadget_giveback_request);
>>
>> +int usb_gadget_register_notify(struct usb_gadget *gadget,
>> +                            struct notifier_block *nb)
>> +{
>> +     unsigned long flags;
>> +     int ret;
>> +
>> +     spin_lock_irqsave(&gadget->lock, flags);
>
> I find you use so many spin_lock_irqsave, any reasons for that?
> Why mutex_lock can't be used?
>

The spin_lock_irqsave() can make it as a atomic notifier, that can
make sure the gadget state event can be quickly reported to the user
who register a notifier on the gadget device. Is it OK?

> --
>
> Best Regards,
> Peter Chen



-- 
Baolin.wang
Best Regards
--
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