From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751268AbbFLEcM (ORCPT ); Fri, 12 Jun 2015 00:32:12 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:36057 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751146AbbFLEcK (ORCPT ); Fri, 12 Jun 2015 00:32:10 -0400 Date: Thu, 11 Jun 2015 21:32:09 -0700 From: Greg Kroah-Hartman To: Lu Baolu Cc: Mathias Nyman , Alan Stern , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] usb: core: lpm: set lpm_capable for root hub device Message-ID: <20150612043209.GA11094@kroah.com> References: <1434072625-7971-1-git-send-email-baolu.lu@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1434072625-7971-1-git-send-email-baolu.lu@linux.intel.com> User-Agent: Mutt/1.5.23+89 (0255b37be491) (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 12, 2015 at 09:29:37AM +0800, Lu Baolu wrote: > Commit 25cd2882e2fc ("usb/xhci: Change how we indicate a host supports > Link PM.") removed the code to set lpm_capable for USB 3.0 super-speed > root hub. The intention of that change was to avoid touching usb core > internal field, a.k.a. lpm_capable, and let usb core to set it by > checking U1 and U2 exit latency values in the descriptor. > > Usb core checks and sets lpm_capable in hub_port_init(). Unfortunately, > root hub is a special usb device as it has no parent. Hub_port_init() > will never be called for a root hub device. That means lpm_capable will > by no means be set for the root hub. As the result, lpm isn't functional > at all in Linux kernel. > > This patch add the code to check and set lpm_capable when registering a > root hub device. It could be back-ported to kernels as old as v3.15, > that contains the Commit 25cd2882e2fc ("usb/xhci: Change how we indicate > a host supports Link PM."). > > Cc: stable@vger.kernel.org # 3.15 > Reported-by: Kevin Strasser > Signed-off-by: Lu Baolu > --- > drivers/usb/core/hcd.c | 6 ++++++ > drivers/usb/core/hub.c | 2 +- > drivers/usb/core/usb.h | 1 + > 3 files changed, 8 insertions(+), 1 deletion(-) > > diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c > index 45a915c..48b208d 100644 > --- a/drivers/usb/core/hcd.c > +++ b/drivers/usb/core/hcd.c > @@ -1032,6 +1032,12 @@ static int register_root_hub(struct usb_hcd *hcd) > } > } > > + if (le16_to_cpu(usb_dev->descriptor.bcdUSB) >= 0x0201) { Why are you treating a binary coded value as a hex number to compare against?