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"?
--
cheers,
-roger
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
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