linux-kernel - Re: [PATCH] usb: xhci: Disable runtime PM suspend for quirky controllers.

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Message-ID: <1594498.BR3TvGka66@linux-5eaq.site>
Date:	Mon, 03 Jun 2013 13:33:13 +0200
From:	Oliver Neukum <oliver@...kum.org>
To:	Don Zickus <dzickus@...hat.com>
Cc:	Sarah Sharp <sarah.a.sharp@...ux.intel.com>,
	Julius Werner <jwerner@...omium.org>,
	Shawn Nematbakhsh <shawnn@...omium.org>,
	Alan Stern <stern@...land.harvard.edu>,
	linux-usb@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] usb: xhci: Disable runtime PM suspend for quirky controllers.

On Wednesday 29 May 2013 16:32:38 Don Zickus wrote:
> On Wed, May 29, 2013 at 12:38:28PM -0700, Sarah Sharp wrote:
> > On Tue, May 28, 2013 at 02:41:18PM -0700, Julius Werner wrote:
> > > The policy we want to achieve is to disable runtime PM iff there is a
> > > device connected that doesn't have persist_enabled or a reset_resume()
> > > handler and whose parent/root hub resets on resume, right?
> > 
> > Makes sense.  However, not all distros may want that policy, so there
> > should be a way to change that policy via sysfs.  Some distros may
> > choose to take the power savings over having a particular USB device
> > work, especially in the server market.
> > 
> > Don, Oliver, what do you think of this patch:
> > http://marc.info/?l=linux-usb&m=136941922715772&w=2
> 
> That is limited only to certain controllers right?  RHEL6 doesn't support
> runtime suspend, so we don't hear to many complaints.  Most of our server
> customers don't have much plugged into USB, so I don't expect much
> problems there.  Our laptop customers prefer the power savings, but I
> don't know how many of them have chipsets with XHCI_RESET_ON_RESUME.

Power savings are good, but reliability is better. For what it's worth,ior
I like the patch. It is a logical extension of the current behavior.

	Regards
		Oliver

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