From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752709AbaETBBl (ORCPT ); Mon, 19 May 2014 21:01:41 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:51133 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752304AbaETBBk (ORCPT ); Mon, 19 May 2014 21:01:40 -0400 Date: Tue, 20 May 2014 10:01:37 +0900 From: Greg KH To: Mathias Nyman Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, sarah.a.sharp@linux.intel.com, Dan Williams , Holger Hans Peter Freyther Subject: Re: [PATCH 02/10] xhci: 'noxhci_port_switch' kernel parameter Message-ID: <20140520010137.GA8146@kroah.com> References: <1399566363-25837-1-git-send-email-mathias.nyman@linux.intel.com> <1399566363-25837-3-git-send-email-mathias.nyman@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1399566363-25837-3-git-send-email-mathias.nyman@linux.intel.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 08, 2014 at 07:25:55PM +0300, Mathias Nyman wrote: > From: Dan Williams > > Add a command line switch for disabling ehci port switchover. Useful > for working around / debugging xhci incompatibilities where ehci > operation is available. > > Reference: http://marc.info/?l=linux-usb&m=138920063001509&w=2 > > Cc: Sarah Sharp > Cc: Mathias Nyman > Cc: Holger Hans Peter Freyther > Suggested-by: Alan Stern > Signed-off-by: Dan Williams > Signed-off-by: Mathias Nyman > --- > Documentation/kernel-parameters.txt | 3 +++ > drivers/usb/host/pci-quirks.c | 15 +++++++++++++-- > 2 files changed, 16 insertions(+), 2 deletions(-) > > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > index 4384217..fc3403114 100644 > --- a/Documentation/kernel-parameters.txt > +++ b/Documentation/kernel-parameters.txt > @@ -2251,6 +2251,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted. > > nox2apic [X86-64,APIC] Do not enable x2APIC mode. > > + noxhci_port_switch > + [USB] Use EHCI instead of XHCI where available > + Ugh, I really don't like new command line options. Especially one that isn't very well documented. Why would someone want to enable this? What problem is it solving? Can we detect this automatically and do it for the user? Is this just for prototype hardware that has not shipped? What hardware needs this? I need a whole lot more documentation at the very least before I will apply this. thanks, greg k-h