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From: Kevin Hilman <khilman@linaro.org>
To: Roger Quadros <rogerq@ti.com>
Cc: <stern@rowland.harvard.edu>, <tony@atomide.com>, <balbi@ti.com>,
	<ruslan.bilovol@ti.com>, <linux-usb@vger.kernel.org>,
	<linux-omap@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [RFC PATCH 4/6] USB: ehci-omap: Suspend the controller during bus suspend
Date: Wed, 19 Jun 2013 10:39:09 -0700	[thread overview]
Message-ID: <87r4fy6lvm.fsf@linaro.org> (raw)
In-Reply-To: <1371650753-11452-5-git-send-email-rogerq@ti.com> (Roger Quadros's message of "Wed, 19 Jun 2013 17:05:51 +0300")

Hi Roger,

Roger Quadros <rogerq@ti.com> writes:

> Runtime suspend the controller during bus suspend and resume it
> during bus resume. This will ensure that the USB Host power domain
> enters lower power state and does not prevent the SoC from
> endering deeper sleep states.
>
> Remote wakeup will come up as an interrupt while the controller
> is suspended, so tackle it carefully using a workqueue.

I don't think you need a special workqueue here.  The workqueue of the PM
core (pm_wq) will be used if you just use an asynchronous 'get' in the
ISR.  Then, the driver's own runtime PM callbacks can be used instead of
an additional workqueue.

Another thing to worry about here when using runtime PM to implement
suspend/resume is that runtime PM can be disabled from userspace (e.g.
echo disabled > /sys/devices/.../power/control.)  If that's the case,
all the pm_runtime_suspended() checks will always fail becuase that
call also checks if runtime PM is disabled.  You'll likely want to use
the pm_runtime_status_suspended() check instead, which checks only the
status, and doesn't matter if runtime PM is currently disabled.

Because of the corner issues here, please test system suspend/resume
when runtime PM has been disabled.

Kevin

  reply	other threads:[~2013-06-19 17:39 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-06-19 14:05 [RFC PATCH 0/6] Suspend USB Host controller on bus suspend Roger Quadros
2013-06-19 14:05 ` [RFC PATCH 1/6] mfd: omap-usb-host: move initialization to module_init() Roger Quadros
2013-06-20 12:07   ` Felipe Balbi
2013-06-20 12:29     ` Roger Quadros
2013-06-19 14:05 ` [RFC PATCH 2/6] mfd: omap-usb-host: Put pins in IDLE state on suspend Roger Quadros
2013-06-19 17:23   ` Kevin Hilman
2013-06-20  7:21     ` Tony Lindgren
2013-06-20 12:30     ` Roger Quadros
2013-06-19 14:05 ` [RFC PATCH 3/6] USB: ehci: allow controller drivers to override irq & bus_suspend/resume Roger Quadros
2013-06-19 14:05 ` [RFC PATCH 4/6] USB: ehci-omap: Suspend the controller during bus suspend Roger Quadros
2013-06-19 17:39   ` Kevin Hilman [this message]
2013-06-20 12:32     ` Roger Quadros
2013-06-20 12:11   ` Felipe Balbi
2013-06-20 12:35     ` Roger Quadros
2013-06-20 17:33       ` Alan Stern
2013-06-24 15:09         ` Roger Quadros
2013-06-24 19:34           ` Alan Stern
2013-06-25 13:59             ` Roger Quadros
2013-06-25 17:38               ` Alan Stern
2013-06-26 13:38                 ` Roger Quadros
2013-06-27 15:40                   ` Alan Stern
2013-06-28 12:20                     ` Roger Quadros
2013-06-28 13:57                       ` Roger Quadros
2013-06-28 19:18                         ` Alan Stern
2013-07-01  8:33                           ` Roger Quadros
2013-06-28 19:06                       ` Alan Stern
2013-07-01  8:16                         ` Roger Quadros
2013-07-01 16:24                           ` Alan Stern
2013-07-01 16:49                             ` Felipe Balbi
2013-07-01 21:01                               ` Alan Stern
2013-07-02  8:22                                 ` Roger Quadros
2013-07-02 17:17                                   ` Alan Stern
2013-07-03  9:13                                     ` Roger Quadros
2013-07-03 12:57                                     ` Felipe Balbi
2013-07-03 13:06                                       ` Roger Quadros
2013-07-03 13:15                                         ` Felipe Balbi
2013-07-03 14:30                                           ` Alan Stern
2013-07-09 13:58                         ` Roger Quadros
2013-06-19 14:05 ` [RFC PATCH 5/6] ARM: dts: omap3beagle-xm: Add idle state pins for USB host Roger Quadros
2013-06-19 18:42   ` Kevin Hilman
2013-06-20 11:55     ` Roger Quadros
2013-06-20 12:02       ` Roger Quadros
2013-06-20 13:02         ` Roger Quadros
2013-06-19 14:05 ` [RFC PATCH 6/6] ARM: OMAP3: Enable Hardware Save and Restore for USB Host Roger Quadros
2013-06-19 17:30   ` Sergei Shtylyov
2013-06-20 12:42     ` Roger Quadros
2013-06-19 15:23 ` [RFC PATCH 0/6] Suspend USB Host controller on bus suspend Alan Stern
2013-06-20 12:39   ` Roger Quadros
2013-06-20 17:19     ` Alan Stern

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