[Letux-kernel] USB3-port on OMAP5432EVM

Roger Quadros rogerq at ti.com
Thu Feb 16 14:47:11 CET 2017


Nikolaus,

On 16/02/17 15:43, H. Nikolaus Schaller wrote:
> Hi Roger,
> I found time to look deeper into this issue and have found it.
> 
>>>
>>> Maybe some u-boot dependency? I use a modified 2016.11.
>>> Should find time do more testing...
>>
>> Yeah. might be a good idea to try different u-boot versions.
>>
>>>
>>> Is there a way to debug what dwc3 is doing or not doing?
>>>
>>
>> You can enable dwc3 trace events.
>>
>> cd /sys/kernel/debug/tracing
>> echo 1 > events/dwc3/enable
> 
> well, I did not find events/dwc3 but a boot log trace of dwc3 failing.
> 
> After checking with printk if the probe function did succeed,
> it turned out that the id pin in extcon-palmas did always return
> -EPROBE_DEFER making the dcw3 driver finally fail to probe.
> 
> This turned out to be a disabled CONFIG_GPIO_PALMAS in our defconfig
> (we do not use the omap2plus). No idea why it was disabled and why
> it did work up to 4.8 or so... Maybe some detail changed in probing
> sequence or dependencies.

Great!!

> 
> Perhaps CONFIG_USB_DWC3_OMAP could enforce CONFIG_GPIO_PALMAS as well.

Unfortunately we can't do that as DWC3_OMAP doesn't need PALMAS to work.
It can even work with GPIOs for VBUS and ID events or some other non-palmas
USB companion chip.

The board specific config must enable CONFIG_GPIO_PALMAS.

> 
> BR and thanks for suggesting to look at tracing/events which directed
> me to the solution,
> Nikolaus
> 
> 

-- 
cheers,
-roger


More information about the Letux-kernel mailing list