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SubjectRe: [PATCH v2] xhci: Set port link to RxDetect if port is not enabled after resume
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> On Apr 23, 2020, at 19:25, Mathias Nyman <mathias.nyman@linux.intel.com> wrote:
>
> On 22.4.2020 16.21, Kai-Heng Feng wrote:
>>
>>
>>> On Mar 26, 2020, at 19:33, Kai-Heng Feng <kai.heng.feng@canonical.com> wrote:
>>>
>>> Hi Mathias,
>>>
>>>> On Mar 11, 2020, at 12:04, Kai-Heng Feng <kai.heng.feng@canonical.com> 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 port is disabled after resume:
>>>> xhci_hcd 0000:3f:00.0: Get port status 4-1 read: 0x280, return 0x280
>
> That sound like the actual problem.
> Any idea how the port link ends up ends up in the disabled state?

Not really. The port link status just became SS.Disabled after S3 wakeup.

> Was there a request to set port feature, link state to SS.Disabled?

No, it was correctly set to U3 prior to system S3.

> Or timeouts at resume from U3
> U3 -> Recovery (timeout) -> Rx.Detect -> Polling (Timeout) -> SS.Disabled

PLS is SS.Disabled, by reading portsc in xhci_bus_resume().

>
>>>>
>>>> According to xHCI 4.19.1.2.1, we should set link to RxDetect to transit
>>>> it from disabled state to disconnected state, which allows the port to
>>>> be set to U0 and completes the resume process.
>>>>
>>>> My own test shows port can still resume when it's not enabled, as long
>>>> as its link is in U states. So constrain the new logic only when link is
>>>> not in any U state.
>
> Sounds more like re-enumerate than proper resume if we go to RxDetect in between

Ok. So should we handle this case inside xhci_bus_resume() or somewhere else?

>
>>>>
>>>> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
>>>
>>> Do you think this is a proper fix?
>>
>> Another gentle ping...
>>
>>>
>>> Kai-Heng
>>>
>>>> ---
>>>> drivers/usb/host/xhci-hub.c | 8 ++++++++
>>>> 1 file changed, 8 insertions(+)
>>>>
>>>> diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
>>>> index a9c87eb8951e..263f9a9237a1 100644
>>>> --- a/drivers/usb/host/xhci-hub.c
>>>> +++ b/drivers/usb/host/xhci-hub.c
>>>> @@ -1776,6 +1776,14 @@ int xhci_bus_resume(struct usb_hcd *hcd)
>>>> clear_bit(port_index, &bus_state->bus_suspended);
>>>> continue;
>>>> }
>>>> +
>>>> + /* 4.19.1.2.1 */
>>>> + if (!(portsc & PORT_PE) && (portsc & PORT_PLS_MASK) > XDEV_U3) {
>>>> + portsc = xhci_port_state_to_neutral(portsc);
>>>> + portsc &= ~PORT_PLS_MASK;
>>>> + portsc |= PORT_LINK_STROBE | XDEV_RXDETECT;
>>>> + }
>>>> +
> This doesn't look like the right solution.
> This will set the link state to RxDetect for any USB3 roothub port
> that is currently not in U0/U1/U2/U3 or Recovery.
>
> 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.

>
> Any other logs or traces that could explan what's going on?

Read port status in xhci_bus_resume():
diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
index f37316d2c8fa..c2e9ac3dc227 100644
--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -1778,7 +1778,7 @@ int xhci_bus_resume(struct usb_hcd *hcd)
port_index = max_ports;
while (port_index--) {
portsc = readl(ports[port_index]->addr);
-
+ xhci_info(xhci, "DEBUG: port %d-%d, portsc 0x%0x pls %d\n", hcd->self.busnum, port_index + 1, portsc, (portsc & PORT_PLS_MASK) >> 5);
/* warm reset CAS limited ports stuck in polling/compliance */
if ((xhci->quirks & XHCI_MISSING_CAS) &&
(hcd->speed >= HCD_USB3) &&
Here's the log. The log is not full because it's too big to upload:
https://pastebin.ubuntu.com/p/24hzqx2nGD/

> Is the resume due to a wakeup (device initiated resume) from this device,
> or just a host initiated resume?

It's a host initiated resume.

>
> Thanks
> -Mathias

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