linux-kernel - Re: [PATCH 5/5] usb: dwc3: dwc3-omap: Disable/Enable core interrupts in Suspend/Resume

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Message-ID: <20140513155019.GN1151@saruman.home>
Date:	Tue, 13 May 2014 10:50:19 -0500
From:	Felipe Balbi <balbi@...com>
To:	George Cherian <george.cherian@...com>
CC:	<linux-kernel@...r.kernel.org>, <linux-omap@...r.kernel.org>,
	<linux-usb@...r.kernel.org>, <balbi@...com>,
	<gregkh@...uxfoundation.org>, <rogerq@...com>, <kishon@...com>
Subject: Re: [PATCH 5/5] usb: dwc3: dwc3-omap: Disable/Enable core interrupts
 in Suspend/Resume

Hi,

On Thu, May 08, 2014 at 03:03:07PM +0530, George Cherian wrote:
> Enabling the core interrupts in complete is too late for XHCI, and stops
> xhci from proper operation. So remove prepare and complete and disable/enable

isn't this a bug in xhci ? I mean the driver should make no assumption
as to when IRQs are enabled, why do we need to enable IRQs earlier when
the device is only considered "ready for use" after ->complete()
finishes executing ?

From documentation we have:

107  * @complete: Undo the changes made by @prepare().  This method is executed for
108  *      all kinds of resume transitions, following one of the resume callbacks:
109  *      @resume(), @thaw(), @restore().  Also called if the state transition
110  *      fails before the driver's suspend callback: @suspend(), @freeze() or
111  *      @poweroff(), can be executed (e.g. if the suspend callback fails for one
112  *      of the other devices that the PM core has unsuccessfully attempted to
113  *      suspend earlier).
114  *      The PM core executes subsystem-level @complete() after it has executed
115  *      the appropriate resume callbacks for all devices.

which tells me that using ->complete() to reenable IRQs is ok here.
Specially when you consider that the role of ->prepare() is to prevent
new children from being created and, for a USB host, that means we
should prevent hub port changes.

cheers

-- 
balbi

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