USB PHY issue in STM32mp157A

[Srikanth1]

Hello,

I am working on a custom board based on STM32MP157A and I am getting all the bits correctly but getting values at reserved bits in USBPHYC version register (Internal) which are supposed to be reserved  as per the reference manual.

Below mentioned screenshots contains :

1.Register from reference manual:

2.Below attached image contains values I am getting when reading the register:

 

And I am confused on how to move forward with usbphy.I hope someone could help me with the problem

Thanks&Regards

Srikanth

 

[PatrickF · Accepted solution]

HI @Srikanth1 

you are right, there is a mistake in the offset of this register in the reference manual. Correct offset is 0x3F4

Thanks to pointing this issue, will be corrected in a future revision of the document.

Regards,

[Srikanth1]

Hi @PatrickF

            Thanks for the reply,now we could read the register correctly.And as of now I am stuck on how to move forward and what can be the next step to be done.

I hope You could help me with forward with the usb.

Thanks &Regards,

srikanth.

[PatrickF]

Hi,

worth to enter a new post describing the issues you encounter with USB.

meanwhile, some useful links

https://wiki.st.com/stm32mpu/wiki/USB_overview

https://wiki.st.com/stm32mpu/wiki/How_to_adjust_USBPHYC_settings_using_USB_Eye_Diagram

Regards.

[Srikanth1]

Hi @PatrickF

I have already referred the links you have mentioned. For USBPHYC i am referring the driver from Linux(V5.13)  and some of the registers  like STM32_USBPHYC_MONITOR mentioned in the driver file are missing in the reference manual (RM0436).So i just wanted to know is it the only register missing in the reference manual (or) are  there any other registers missing .If yes, could you help me in finding those registers with their offset addresses and their functionality  or suggest me the  actual  reference manual.

please find the below attached link for the driver file i am using :

https://elixir.bootlin.com/linux/v5.13/source/drivers/phy/st/phy-stm32-usbphyc.c

Thanks&Regards,

Srikanth.

[PatrickF]

Hi,

This missing register should be present in a future revision of the STM32MP15 reference manual.
Meanwhile, you could find it in the STM32MP13 reference manual (RM0475) which uses same USBPHYC.

There is some missing IP identification registers which are missing, but read-only and not used by the driver. For the sake of completeness, those will be added too.

Btw, I will correct my first answer as USBPHYC_VERR register offset if 0x3F4 (0xFF4 is true, but is a mirroring view). Will be corrected as well in RM0475.

Regards