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[220.133.187.190]) by smtp.gmail.com with ESMTPSA id w13sm3396670pfn.192.2020.05.06.21.52.29 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 06 May 2020 21:52:30 -0700 (PDT) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 13.4 \(3608.80.23.2.2\)) Subject: Re: [PATCH v2] xhci: Set port link to RxDetect if port is not enabled after resume From: Kai-Heng Feng In-Reply-To: Date: Thu, 7 May 2020 12:52:28 +0800 Cc: Mathias Nyman , Greg Kroah-Hartman , Alan Stern , "open list:USB NETWORKING DRIVERS" , linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8BIT Message-Id: <79060777-FF5B-4394-9A05-8573B6EF6578@canonical.com> References: <20200311040456.25851-1-kai.heng.feng@canonical.com> <635B3350-F064-4B45-B194-40F793423049@canonical.com> <35fbb517-31b1-7bba-8e07-795ab18af1ff@linux.intel.com> <47BCEDDA-2E91-4CE3-AA45-B2EEB1DA111D@canonical.com> To: Mathias Nyman X-Mailer: Apple Mail (2.3608.80.23.2.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Apr 28, 2020, at 00:49, Mathias Nyman wrote: > > On 27.4.2020 12.05, Kai-Heng Feng wrote: >> >> >>> On Apr 23, 2020, at 19:25, Mathias Nyman wrote: >>> >>> Was this roothub port forcefully suspended xhci_bus_suspend()? >>> i.e. was a bit set in bus_state->bus_suspended for this port? >> >> No, it's a USB3 device so it was set to U3 via USB_PORT_FEAT_LINK_STATE. > > Logs show port was first forced by xhci_bus_suspend() to U3 ("port 0 not > suspended" message) > and only later set to U3 by USB_PORT_FEAT_LINK_STATE. > Seems line wrong order or race. The "port 0 not suspended" is actually for 3-1, if we print bus num and port + 1: [ 213.732977] xhci_hcd 0000:3f:00.0: port 3-1 not suspended For port 4-1 it's always suspended before suspend the bus. I'll send a patch to adjust the debug message for better clarity. > > while suspended we get a port event about a connect status change, > showing port link state is in disabled. > Cherry picked messages: > > [ 1330.021450] xhci_hcd 0000:3f:00.0: port 0 not suspended > [ 1330.036822] xhci_hcd 0000:3f:00.0: Set port 4-1 link state, portsc: 0x1203, write 0x11261 > [ 1331.020736] xhci_hcd 0000:3f:00.0: Port change event, 4-1, id 1, portsc: 0x20280 > [ 1331.020738] xhci_hcd 0000:3f:00.0: resume root hub > [ 1331.020741] xhci_hcd 0000:3f:00.0: handle_port_status: starting port polling. > > If we force the port link state to U3 in xhci_bus_suspend() maybe it would make > sense to try and recover it in xhci_bus_resume(). But only for that forced > port. > > None of the previous suspend/resume cycles in the logs went smooth either. > Each time device 4-1 was forced to U3 bus xhci_bus_suspend(), and at resume the > link was stuck in polling until timeout, after which it went to compliance mode, > and had to be warm reset to recover. If my observation above is true, port 4-1 is indeed suspended by usb_port_suspend() rather than xhci_bus_suspend(). > > We could add the code to recover USB3 ports from disabled state in case we > forced them to U3, but the rootcause of theus suspend/resume issues should > be found as well Seems like the issue doesn't happen if the host system use S2Idle instead of S3. However, I can't see any difference in xHCI driver with different suspend methods. Maybe the root cause is that, ASMedia controller and SMSC hub are just quirky? > > Limiting your code to USB3 devices that xhi_bus_suspend forced to U3 would look > something like this: > > diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c > index 9eca1fe81061..0f16dd936ab8 100644 > --- a/drivers/usb/host/xhci-hub.c > +++ b/drivers/usb/host/xhci-hub.c > @@ -1789,6 +1789,15 @@ int xhci_bus_resume(struct usb_hcd *hcd) > case XDEV_RESUME: > /* resume already initiated */ > break; > + case XDEV_DISABLED: > + if (hcd->speed >= HCD_USB3) { > + portsc = xhci_port_state_to_neutral( > + portsc); > + portsc &= ~PORT_PLS_MASK; > + portsc |= PORT_LINK_STROBE | > + XDEV_RXDETECT; > + } > + /* fall through for both USB3 abd USB2 */ > default: > /* not in a resumeable state, ignore it */ > clear_bit(port_index, This doesn't work because port 4-1 isn't suspended by xhci_bus_suspend(). Maybe we can restrict the case to ports that are suspended by USB_PORT_FEAT_LINK_STATE. Is the following patch looks good to you? diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c index f37316d2c8fa..dc2e14ea308d 100644 --- a/drivers/usb/host/xhci-hub.c +++ b/drivers/usb/host/xhci-hub.c @@ -1787,6 +1787,16 @@ int xhci_bus_resume(struct usb_hcd *hcd) clear_bit(port_index, &bus_state->bus_suspended); continue; } + + if (bus_state->suspended_ports & (1 << port_index)) { + if ((portsc & PORT_PLS_MASK) == XDEV_DISABLED && + hcd->speed >= HCD_USB3) { + portsc = xhci_port_state_to_neutral(portsc); + portsc &= ~PORT_PLS_MASK; + portsc |= PORT_LINK_STROBE | XDEV_RXDETECT; + } + } + /* resume if we suspended the link, and it is still suspended */ if (test_bit(port_index, &bus_state->bus_suspended)) switch (portsc & PORT_PLS_MASK) { Kai-Heng > > -Mathias