From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752418AbbFLRnR (ORCPT ); Fri, 12 Jun 2015 13:43:17 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:58137 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1750861AbbFLRnO (ORCPT ); Fri, 12 Jun 2015 13:43:14 -0400 Date: Fri, 12 Jun 2015 13:43:13 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Lu Baolu cc: Mathias Nyman , Greg Kroah-Hartman , , Subject: Re: [PATCH 1/1] usb: core: lpm: set lpm_capable for root hub device In-Reply-To: <1434072625-7971-1-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 On Fri, 12 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 > --- > 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) { > + retval = usb_get_bos_descriptor(usb_dev); > + if (!retval) > + usb_dev->lpm_capable = usb_device_supports_lpm(usb_dev); > + } > + This should be integrated with the code immediately above it, which also calls usb_get_bos_descriptor(). In fact, maybe you should simply change the existing code to check bcdUSB >= 0x0201 instead of speed == USB_SPEED_SUPER. > retval = usb_new_device (usb_dev); > if (retval) { > dev_err (parent_dev, "can't register root hub for %s, %d\n", > diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c > index 3b71516..884d702 100644 > --- a/drivers/usb/core/hub.c > +++ b/drivers/usb/core/hub.c > @@ -122,7 +122,7 @@ struct usb_hub *usb_hub_to_struct_hub(struct usb_device *hdev) > return usb_get_intfdata(hdev->actconfig->interface[0]); > } > > -static int usb_device_supports_lpm(struct usb_device *udev) > +int usb_device_supports_lpm(struct usb_device *udev) > { > /* USB 2.1 (and greater) devices indicate LPM support through > * their USB 2.0 Extended Capabilities BOS descriptor. > diff --git a/drivers/usb/core/usb.h b/drivers/usb/core/usb.h > index 7eb1e26..d5668c4 100644 > --- a/drivers/usb/core/usb.h > +++ b/drivers/usb/core/usb.h > @@ -82,6 +82,7 @@ extern int usb_runtime_suspend(struct device *dev); > extern int usb_runtime_resume(struct device *dev); > extern int usb_runtime_idle(struct device *dev); > extern int usb_set_usb2_hardware_lpm(struct usb_device *udev, int enable); > +extern int usb_device_supports_lpm(struct usb_device *udev); > > #else This will break if you build it with CONFIG_PM disabled. Alan Stern