Re: [RFC PATCH 0/6] Suspend USB Host controller on bus suspend

From: Alan Stern <stern@rowland.harvard.edu>
To: Roger Quadros <rogerq@ti.com>
Cc: 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 0/6] Suspend USB Host controller on bus suspend
Date: Thu, 20 Jun 2013 13:19:31 -0400 (EDT)	[thread overview]
Message-ID: <Pine.LNX.4.44L0.1306201314160.2063-100000@iolanthe.rowland.org> (raw)
In-Reply-To: <51C2F807.1000301@ti.com>

On Thu, 20 Jun 2013, Roger Quadros wrote:

> >> As the omap-ehci controller driver needs to do some additional work to put
> >> itself into suspend/resume and make sure it is resumed to process an interrupt,
> >> we need to be able to override irq, bus_suspend, and bus_resume handlers. This
> >> provision is done in patch 3.
> > 
> > Do you still need to override these things if you do the controller
> > suspend at the right time?
> > 
> 
> At least not for bus_suspend and bus_resume. We will still need to override the irq
> handler though. But, if we can take care of this generically in the ehci_irq handler (i.e. make
> sure controller is not suspended while accessing it) then we don't need such override
> for irq.

I don't think you need to override anything.  The high-level interrupt
handler usb_hcd_irq() will avoid calling ehci_irq() when the
HCD_HW_ACCESSIBLE flag isn't set.  All you will need to do in
ehci-omap.c is call synchronize_irq() after ehci_suspend() returns and
before turning off the clocks.

Alan Stern