>
> On 05/11/2012 03:53 AM, Quach, Brian wrote:
>> Hello,
>>
>> I work for Texas Instruments on the group that develops our USB 3.0 products.
>> Recently, we discovered a timing issue in our USB3.0 re-drivers that
>> can delay the negotiation between a device and the host past the
>> usual handshake timeout, and if that happens on the first insertion,
>> the host controller port will enter in Compliance mode as per the
>> xHCI spec. The host controller does not generate a Port Status Change
>> (PSC) event as a result of a transition to compliance mode so the
>> only way method to detect and resolve the issue is to periodically
>> poll the port to check for compliance mode and issue a Warm Reset to
>> recover the port. This polling is only required if the port had never previously entered U0.
>>
>
> Does xHCI driver see this transition in GetPortStatus when it occurs?
>
>> We implemented a small app to monitor the device's PORTSC registers
>> and to issue a warm reset whenever we find the port is in compliance
>> mode. Although this seems to work-around the issue, we believe this
>> should be implemented on the driver source code for robustness.
>>
>> Due to your bandwidth limitations, I was told that we should be
>> making our own patches and submitting them to you for integration into the mainline.
>> Based on the information I provided about the issue, can you provide
>> any advice on how/where the source code the patch should be
>> implemented so that it will be acceptable for the mainline and
>> whether it should be a menuconfig option.
>>
>
> Currently USB3.0 driver support warm reset and it will issue a warm
> reset when detects a port in SS.Inactive state. See the code from
> drivers/usb/core/hub.c:hub_events():
>
> /* Warm reset a USB3 protocol port if it's in
> * SS.Inactive state.
> */
> if (hub_is_superspeed(hub->hdev) &&
> (portstatus & USB_PORT_STAT_LINK_STATE)
> == USB_SS_PORT_LS_SS_INACTIVE) {
> dev_dbg(hub_dev, "warm reset port
> %d\n", i);
> hub_port_reset(hub, i, NULL,
> HUB_BH_RESET_TIME,
> true);
> }
>
> You can perform similar steps for a port in compliance mode if xHCI
> driver can detect the port status.
>
> Thanks,
> Andiry
>
>
Hello Andiry,
We really appreciate your feedback. We will confirm this and get back to you ASAP.
Thanks,
Jorge.
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