linux-kernel - Re: [RFC v6 3/3] usb: phy: hold wakeupsource when USB is enumerated in peripheral mode

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Date:	Tue, 18 Nov 2014 22:21:20 +0530
From:	Kiran Raparthy <kiran.kumar@...aro.org>
To:	Felipe Balbi <balbi@...com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Todd Poynor <toddpoynor@...gle.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-usb@...r.kernel.org,
	Android Kernel Team <kernel-team@...roid.com>,
	John Stultz <john.stultz@...aro.org>,
	Sumit Semwal <sumit.semwal@...aro.org>,
	Arve Hj�nnev�g <arve@...roid.com>,
	Benoit Goby <benoit@...roid.com>
Subject: Re: [RFC v6 3/3] usb: phy: hold wakeupsource when USB is enumerated
 in peripheral mode

On 18 November 2014 21:25, Felipe Balbi <balbi@...com> wrote:
> Hi,
>
> On Wed, Nov 12, 2014 at 12:11:19PM +0530, Kiran Kumar Raparthy wrote:
>> From: Todd Poynor <toddpoynor@...gle.com>
>>
>> usb: phy: hold wakeupsource when USB is enumerated in peripheral mode
>>
>> Some systems require a mechanism to prevent system to enter into suspend
>> state when USB is connected and enumerated in peripheral mode.
>>
>> This patch provides an interface to hold a wakeupsource to prevent suspend.
>> PHY drivers can use this interface when USB is connected and enumerated in
>> peripheral mode.
>>
>> A timed wakeupsource is temporarily held on USB disconnect events, to allow
>> the rest of the system to react to the USB disconnection (dropping host
>> sessions, updating charger status, etc.) prior to re-allowing suspend.
>>
>> Cc: Felipe Balbi <balbi@...com>
>> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
>> Cc: linux-kernel@...r.kernel.org
>> Cc: linux-usb@...r.kernel.org
>> Cc: Android Kernel Team <kernel-team@...roid.com>
>> Cc: John Stultz <john.stultz@...aro.org>
>> Cc: Sumit Semwal <sumit.semwal@...aro.org>
>> Cc: Arve Hj�nnev�g <arve@...roid.com>
>> Cc: Benoit Goby <benoit@...roid.com>
>> Signed-off-by: Todd Poynor <toddpoynor@...gle.com>
>> [kiran: Added context to commit message, squished build fixes
>> from Benoit Goby and Arve Hjønnevåg, changed wakelocks usage
>> to wakeupsource, merged Todd's refactoring logic and simplified
>> the structures and code and addressed community feedback]
>> Signed-off-by: Kiran Raparthy <kiran.kumar@...aro.org>
>> ---
>>  drivers/usb/phy/phy.c   | 29 +++++++++++++++++++++++++++--
>>  include/linux/usb/phy.h |  5 +++++
>>  2 files changed, 32 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/usb/phy/phy.c b/drivers/usb/phy/phy.c
>> index 2b1039e..b5c5fd3 100644
>> --- a/drivers/usb/phy/phy.c
>> +++ b/drivers/usb/phy/phy.c
>> @@ -329,6 +329,7 @@ int usb_add_phy(struct usb_phy *x, enum usb_phy_type type)
>>       int             ret = 0;
>>       unsigned long   flags;
>>       struct usb_phy  *phy;
>> +     char wsource_name[40];
>>
>>       if (x->type != USB_PHY_TYPE_UNDEFINED) {
>>               dev_err(x->dev, "not accepting initialized PHY %s\n", x->label);
>> @@ -351,6 +352,10 @@ int usb_add_phy(struct usb_phy *x, enum usb_phy_type type)
>>       x->type = type;
>>       list_add_tail(&x->head, &phy_list);
>>
>> +     snprintf(wsource_name, sizeof(wsource_name), "vbus-%s",
>> +             dev_name(x->dev));
>> +     wakeup_source_init(&x->wsource, wsource_name);
>
> do you really need the device name on the wakeup source or would
> usb-vbus suffice ? Hmm, I guess we could have several of these in the
> same system, so maybe there's no other way.
yeah true.
>
>> @@ -446,13 +452,32 @@ int usb_bind_phy(const char *dev_name, u8 index,
>>  EXPORT_SYMBOL_GPL(usb_bind_phy);
>>
>>  /**
>> - * usb_phy_set_event - set event to phy event
>> + * usb_phy_set_event - set event to phy event and
>> + * hold/temporarily hold wakeupsource
>>   * @x: the phy returned by usb_get_phy();
>>   *
>> - * This sets event to phy event
>> + * This holds per-PHY wakeupsource/timed wakeupsource
>>   */
>>  void usb_phy_set_event(struct usb_phy *x, unsigned long event)
>>  {
>> +
>>       x->last_event = event;
>> +
>> +     switch (event) {
>> +     case USB_EVENT_ENUMERATED:
>> +             __pm_stay_awake(&x->wsource);
>> +             break;
>> +
>> +     case USB_EVENT_NONE:
>> +     case USB_EVENT_ID:
>> +     case USB_EVENT_VBUS:
>> +     case USB_EVENT_CHARGER:
>> +             __pm_wakeup_event(&x->wsource,
>> +                             msecs_to_jiffies(TEMPORARY_HOLD_TIME));
>> +             break;
>> +
>> +     default:
>> +             break;
>> +     }
>
> much, much better. Completely hidden from PHY drivers.
>
>>  }
>>  EXPORT_SYMBOL_GPL(usb_phy_set_event);
>> diff --git a/include/linux/usb/phy.h b/include/linux/usb/phy.h
>> index 3c713ff..bc58fb8 100644
>> --- a/include/linux/usb/phy.h
>> +++ b/include/linux/usb/phy.h
>> @@ -12,6 +12,8 @@
>>  #include <linux/notifier.h>
>>  #include <linux/usb.h>
>>
>> +#define TEMPORARY_HOLD_TIME    2000
>
> minor nit:
>
> Let's call this:
>
> #define USB_PHY_DEFAULT_WAKEUP_SRC_TIMEOUT      2000 /* ms */
>
> When resending, please drop that "RFC" from subject and make sure your
> series is sent as a single thread, instead of three separate patches.
Sure Felipe,Thanks for your time.
>
> cheers
>
> --
> balbi
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