Re: [PATCH] usb: host: ehci: workaround PME bug on AMD EHCI controller

Kai-Heng Feng
2017-06-16T03:07:46Z

On Thu, Jun 15, 2017 at 10:12 PM, Alan Stern <stern@rowland.harvard.edu> wrote:
> On Thu, 15 Jun 2017, Kai-Heng Feng wrote:
>
>> On Wed, Jun 14, 2017 at 1:28 AM, Bjorn Helgaas <helgaas@kernel.org> wrote:
>> >
>> > The lspci output [1] shows:
>> >
>> > 00:12.0 USB controller: Advanced Micro Devices, Inc. [AMD] FCH USB EHCI Controller (rev 39) (prog-if 20 [EHCI])
>> > Capabilities: [c0] Power Management version 2
>> > Flags: PMEClk- DSI- D1+ D2+ AuxCurrent=0mA PME(D0+,D1+,D2+,D3hot+,D3cold+)
>> > Status: D3 NoSoftRst- PME-Enable+ DSel=0 DScale=0 PME-
>> > Bridge: PM- B3+
>> >
>> > The device claims it can assert PME# from D3hot. If it can't, that
>> > sounds like a hardware defect that should be addressed with a quirk.
>> > Ideally we would also have a pointer to the AMD hardware erratum.
>>
>> Looks like it's pretty similar to "23 USB Wake on Connect/Disconnect
>> with Low Speed Devices" in [1].
>> It points to a workaround in appendix A2 from [2].
>> However it says this bug only effects Low Speed devices, but it
>> actually also happens on High Speed devices.
>>
>> [1] https://support.amd.com/TechDocs/46837.pdf
>> [2] https://support.amd.com/TechDocs/42413.pdf
>
> Those documents refer to a hardware bug with a workaround in the BIOS.
> Have you checked to see if your BIOS is up to date?

Yes, it's up to date.

>
> Alan Stern
>