Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965014AbaFJArG (ORCPT ); Mon, 9 Jun 2014 20:47:06 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:58169 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932880AbaFJAV4 (ORCPT ); Mon, 9 Jun 2014 20:21:56 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alan Stern , Will Deacon Subject: [PATCH 3.4 16/88] USB: Avoid runtime suspend loops for HCDs that cant handle suspend/resume Date: Mon, 9 Jun 2014 17:24:26 -0700 Message-Id: <20140610002425.068184009@linuxfoundation.org> X-Mailer: git-send-email 1.9.0 In-Reply-To: <20140610002424.500996570@linuxfoundation.org> References: <20140610002424.500996570@linuxfoundation.org> User-Agent: quilt/0.63-1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Alan Stern commit 8ef42ddd9a53b73e6fc3934278710c27f80f324f upstream. Not all host controller drivers have bus-suspend and bus-resume methods. When one doesn't, it will cause problems if runtime PM is enabled in the kernel. The PM core will attempt to suspend the controller's root hub, the suspend will fail because there is no bus-suspend routine, and a -EBUSY error code will be returned to the PM core. This will cause the suspend attempt to be repeated shortly thereafter, in a never-ending loop. Part of the problem is that the original error code -ENOENT gets changed to -EBUSY in usb_runtime_suspend(), on the grounds that the PM core will interpret -ENOENT as meaning that the root hub has gotten into a runtime-PM error state. While this change is appropriate for real USB devices, it's not such a good idea for a root hub. In fact, considering the root hub to be in a runtime-PM error state would not be far from the truth. Therefore this patch updates usb_runtime_suspend() so that it adjusts error codes only for non-root-hub devices. Furthermore, the patch attempts to prevent the problem from occurring in the first place by not enabling runtime PM by default for root hubs whose host controller driver doesn't have bus_suspend and bus_resume methods. Signed-off-by: Alan Stern Reported-by: Will Deacon Tested-by: Will Deacon Signed-off-by: Greg Kroah-Hartman --- drivers/usb/core/driver.c | 9 ++++++--- drivers/usb/core/hub.c | 15 +++++++++++++-- 2 files changed, 19 insertions(+), 5 deletions(-) --- a/drivers/usb/core/driver.c +++ b/drivers/usb/core/driver.c @@ -1708,10 +1708,13 @@ int usb_runtime_suspend(struct device *d if (status == -EAGAIN || status == -EBUSY) usb_mark_last_busy(udev); - /* The PM core reacts badly unless the return code is 0, - * -EAGAIN, or -EBUSY, so always return -EBUSY on an error. + /* + * The PM core reacts badly unless the return code is 0, + * -EAGAIN, or -EBUSY, so always return -EBUSY on an error + * (except for root hubs, because they don't suspend through + * an upstream port like other USB devices). */ - if (status != 0) + if (status != 0 && udev->parent) return -EBUSY; return status; } --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -1401,8 +1401,19 @@ static int hub_probe(struct usb_interfac desc = intf->cur_altsetting; hdev = interface_to_usbdev(intf); - /* Hubs have proper suspend/resume support. */ - usb_enable_autosuspend(hdev); + /* + * Hubs have proper suspend/resume support, except for root hubs + * where the controller driver doesn't have bus_suspend and + * bus_resume methods. + */ + if (hdev->parent) { /* normal device */ + usb_enable_autosuspend(hdev); + } else { /* root hub */ + const struct hc_driver *drv = bus_to_hcd(hdev->bus)->driver; + + if (drv->bus_suspend && drv->bus_resume) + usb_enable_autosuspend(hdev); + } if (hdev->level == MAX_TOPO_LEVEL) { dev_err(&intf->dev, -- 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/