Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932172AbbFOOVO (ORCPT ); Mon, 15 Jun 2015 10:21:14 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:52025 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1755121AbbFOOVD (ORCPT ); Mon, 15 Jun 2015 10:21:03 -0400 Date: Mon, 15 Jun 2015 10:21:02 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Lu Baolu cc: Mathias Nyman , Greg Kroah-Hartman , , Subject: Re: [PATCH v3 1/1] usb: core: lpm: set lpm_capable for root hub device In-Reply-To: <1434337199-24500-1-git-send-email-baolu.lu@linux.intel.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1412 Lines: 30 On Mon, 15 Jun 2015, 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 Acked-by: Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/