Hi Martin,

On Tue, 21 Sept 2021 at 00:56, Martin Blumenstingl
[off-list ref] wrote:

Hi Anand,

On Tue, Aug 31, 2021 at 10:48 PM Anand Moon [off-list ref] wrote:
[...]

quoted

After enabling CONFIG_REGULATOR_DEBUG, with this patch applied
I still not getting the USB regulator to enable.
Do you see different output at your end?

I don't have much time for testing and debugging currently but I'll
put it on my TODO-list
Until either of us has found the issue I suggest not merging this patch.

Ok no problem.

Basically, I have just roughly gone through the architecture of
Amlogic's OTG framework.
Below is the global configuration registers for DWC2 OTG framer work

[0] https://github.com/hardkernel/linux/blob/odroidc-3.10.y/drivers/amlogic/usb/dwc_otg/310/dwc_otg_regs.h#L66-L151

Within some configurations, it helps tune the power for vbus and interrupt
For example
[1] https://github.com/hardkernel/linux/blob/odroidc-3.10.y/drivers/amlogic/usb/dwc_otg/310/dwc_otg_attr.c#L666-L717

Amlogic basically used the mode parameter to external tune the DWC2 driver
it could help more fine-tuning the driver.

[2] https://github.com/hardkernel/linux/blob/odroidc-3.10.y/drivers/amlogic/usb/dwc_otg/310/dwc_otg_driver.c#L1461-L1703

I feel we need to identify many more PHY tuning parameters to make the
USB work correctly.






Thanks
-Anand

Best regards,
Martin

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