Hi,
On 10/31/2017 4:12 PM, Felipe Balbi wrote:
> Hi,
>
> Roger Quadros <rogerq@xxxxxx> writes:
>> On 31/10/17 12:24, Felipe Balbi wrote:
>>> Hi,
>>>
>>> Roger Quadros <rogerq@xxxxxx> writes:
>>>
>>> <snip>
>>>
>>>>> Roger, your PHY is toast :-(
>>>>>
>>>>> irq/90-dwc3-969 [000] d... 52.323145: dwc3_event: event (00000901): Erratic Error [U0]
>>>>> irq/90-dwc3-969 [000] d... 52.560646: dwc3_event: event (00000901): Erratic Error [U0]
>>>>> irq/90-dwc3-969 [000] d... 52.798144: dwc3_event: event (00000901): Erratic Error [U0]
>>>>> irq/90-dwc3-969 [000] d... 53.035646: dwc3_event: event (00000901): Erratic Error [U0]
>>>>> irq/90-dwc3-969 [000] d... 53.273143: dwc3_event: event (00000901): Erratic Error [U0]
>>>>> irq/90-dwc3-969 [000] d... 53.510657: dwc3_event: event (00000901): Erratic Error [U0]
>>>>> irq/90-dwc3-969 [000] d... 53.748142: dwc3_event: event (00000901): Erratic Error [U0]
>>>>> irq/90-dwc3-969 [000] d... 53.985640: dwc3_event: event (00000901): Erratic Error [U0]
>>>>>
>>>> This is known issue due to operating a HighSpeed PHY in SuperSpeed mode.
>>>>
>>>> from dwc3/gadget.c:2015
>>>>
>>>> /*
>>>> * WORKAROUND: DWC3 revision < 2.20a have an issue
>>>> * which would cause metastability state on Run/Stop
>>>> * bit if we try to force the IP to USB2-only mode.
>>>> *
>>>> * Because of that, we cannot configure the IP to any
>>>> * speed other than the SuperSpeed
>>>> *
>>>> * Refers to:
>>>> *
>>>> * STAR#9000525659: Clock Domain Crossing on DCTL in
>>>> * USB 2.0 Mode
>>>> */
>>>> if (dwc->revision < DWC3_REVISION_220A) {
>>>> reg |= DWC3_DCFG_SUPERSPEED;
>>>> } else {
>>>>
>>>> If we undo this workaround, the Erratic Error messages should go away.
>>> right, I remember now. It's your call, if you wanna add a flag to ignore
>>> this STAR ticket, just keep in mind you'd have to cope with possible
>>> metastability on the Run/Stop bit :-)
>>>
>> The TI kernel releases have been ignoring this workaround for quite sometime now and
>> there haven't been any surprises.
>> I'd be happy to have a flag so I don't have to keep porting a patch around :).
>>
>> Should I add a DT property?
>> "snps,dis_metastability_quirk"?
> Sure, we can send that on the next merge window (v4.15). Just make sure
> to REALLY make it clear that this is a dangerous flag and should only be
> enabled if you really, really know what you're doing :-)
If SSPHY is not present on this platform(?) or maximum_speed = HS then we can
avoid overriding max-speed to SS?
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