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[61.220.137.37]) by smtp.gmail.com with ESMTPSA id t8sm8783700pji.11.2019.11.04.21.14.18 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 04 Nov 2019 21:14:19 -0800 (PST) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 13.0 \(3594.4.19\)) Subject: Re: [PATCH 2/2] usb: core: Attempt power cycle when port is in eSS.Disabled state From: Kai Heng Feng In-Reply-To: <20191104143838.GA2183570@kroah.com> Date: Tue, 5 Nov 2019 13:14:16 +0800 Cc: Alan Stern , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8BIT Message-Id: References: <20191007182840.4867-1-kai.heng.feng@canonical.com> <20191007182840.4867-2-kai.heng.feng@canonical.com> <20191104143838.GA2183570@kroah.com> To: Greg KH X-Mailer: Apple Mail (2.3594.4.19) Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org > On Nov 4, 2019, at 10:38 PM, Greg KH wrote: > > On Tue, Oct 08, 2019 at 02:28:40AM +0800, Kai-Heng Feng wrote: >> On Dell TB16, Realtek USB ethernet (r8152) connects to an SMSC hub which >> then connects to ASMedia xHCI's root hub: >> >> /: Bus 04.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/2p, 5000M >> |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/7p, 5000M >> |__ Port 2: Dev 3, If 0, Class=Vendor Specific Class, Driver=r8152, 5000M >> >> Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub >> Bus 004 Device 002: ID 0424:5537 Standard Microsystems Corp. USB5537B >> Bus 004 Device 003: ID 0bda:8153 Realtek Semiconductor Corp. RTL8153 Gigabit Ethernet Adapter >> >> The SMSC hub may disconnect after system resume from suspend. When this >> happens, the reset resume attempt fails, and the last resort to disable >> the port and see something comes up later, also fails. >> >> When the issue occurs, the link state stays in eSS.Disabled state >> despite the warm reset attempts. The USB spec mentioned this can be >> caused by invalid VBus, and after some expiremets, it does show that the >> SMSC hub can be brought back after a power cycle. >> >> So let's power cycle the port at the end of reset resume attempt, if >> it's in eSS.Disabled state. >> >> Signed-off-by: Kai-Heng Feng >> --- >> drivers/usb/core/hub.c | 21 +++++++++++++++++++-- >> 1 file changed, 19 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c >> index 6655a6a1651b..5f50aca7cf67 100644 >> --- a/drivers/usb/core/hub.c >> +++ b/drivers/usb/core/hub.c >> @@ -2739,20 +2739,33 @@ static bool hub_port_warm_reset_required(struct usb_hub *hub, int port1, >> || link_state == USB_SS_PORT_LS_COMP_MOD; >> } >> >> +static bool hub_port_power_cycle_required(struct usb_hub *hub, int port1, >> + u16 portstatus) >> +{ >> + u16 link_state; >> + >> + if (!hub_is_superspeed(hub->hdev)) >> + return false; >> + >> + link_state = portstatus & USB_PORT_STAT_LINK_STATE; >> + return link_state == USB_SS_PORT_LS_SS_DISABLED; >> +} >> + >> static void hub_port_power_cycle(struct usb_hub *hub, int port1) >> { >> + struct usb_port *port_dev = hub->ports[port1 - 1]; >> int ret; >> >> ret = usb_hub_set_port_power(hub, port1, false); >> if (ret) { >> - dev_info(&udev->dev, "failed to disable port power\n"); >> + dev_info(&port_dev->dev, "failed to disable port power\n"); >> return; >> } >> >> msleep(2 * hub_power_on_good_delay(hub)); >> ret = usb_hub_set_port_power(hub, port1, true); >> if (ret) { >> - dev_info(&udev->dev, "failed to enable port power\n"); >> + dev_info(&port_dev->dev, "failed to enable port power\n"); >> return; >> } >> >> @@ -3600,6 +3613,10 @@ int usb_port_resume(struct usb_device *udev, pm_message_t msg) >> if (status < 0) { >> dev_dbg(&udev->dev, "can't resume, status %d\n", status); >> hub_port_logical_disconnect(hub, port1); >> + if (hub_port_power_cycle_required(hub, port1, portstatus)) { >> + dev_info(&udev->dev, "device in disabled state, attempt power cycle\n"); > > Why dev_info()? Shouldn't we only care if this fails? I’ll lower the level to dev_dbg(). > >> + hub_port_power_cycle(hub, port1); > > Weren't we only going to do this for the broken types of devices? And > not for everything? >From what I can understand from the spec, if the device is in eSS.Disabled state, there’s no way out. So "power cycling as a last resort” is indeed targets everything. Kai-Heng > thanks, > > greg k-h