From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755241AbbFMAMo (ORCPT ); Fri, 12 Jun 2015 20:12:44 -0400 Received: from mga02.intel.com ([134.134.136.20]:20466 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752795AbbFMAMj (ORCPT ); Fri, 12 Jun 2015 20:12:39 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.13,605,1427785200"; d="scan'208";a="745860138" Message-ID: <557B7573.5000002@linux.intel.com> Date: Sat, 13 Jun 2015 08:12:35 +0800 From: "Lu, Baolu" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Alan Stern CC: Mathias Nyman , Greg Kroah-Hartman , 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 References: In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/13/2015 01:43 AM, Alan Stern wrote: > 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. I agree with you and will change it in v2 patch. > >> 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. Yes. Will fix it in v2 patch. > > Alan Stern Thank you, Baolu > > -- > 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/ > >