[PATCH] usb: dwc2: add "u-boot,force-vbus-detection" for stm32

[Patrick DELAUNAY]

Hi Marek,

> From: Marek Vasut <marex at denx.de>
> Sent: jeudi 15 octobre 2020 15:08
> 
> On 10/15/20 2:49 PM, Patrick Delaunay wrote:
> > On some board, the ID pin is not connected so the B session must be
> > overridden with "u-boot,force_b_session_valid" but the VBus sensing
> > must continue to be handle.
> >
> > To managed it, this patch adds a new DT field
> > "u-boot,force-vbus-detection" to use with "u-boot,force_b_session_valid"
> 
> How is this solved in Linux ?

It is managed by Linux DWC2 driver: it is a real OTG driver, with dual mode
support and by usb framework

Throught the properties
&usbotg_hs {
	usb-role-switch;
};

a glue treat the session and the sensing management
see linux/drivers/usb/dwc2/drd.c in linux-next

PS: activate_stm_id_vb_detection is also used in driver = hsotg->params. 

As ID pin / vbus is completly managed by the USB TYPE driver C
(STUSB1600 for STMicroelectronics board) and DWC2 driver with dual role
stack (host/gadget).

I don't found a better solution than device tree property for this task in U-Boot as DWC2
driver don't support dual role and U-Boot don't have framework for USB type C controller.

> 
> btw can you do something about that huge change in indent ? Is it necessary ?

I move all this code under activate_stm_id_vb_detection (linked to compatible "st,stm32mp1-hsotg")
to avoid impact on other platform as this "sensing" properties are only support for STM32MP15X
(it is linked to USB block detection integrated in SOC)

And after I need to check the 
1/ The usb33d-supply is required of vbus or IDPIN sensing
2/ manage Vbus sensing or override (according dt)
3/ manage IDPIN or override (according dt)

I add a new property to be backward compatible (even it the combinaison is less clear)
I protect regulator function call to avoid compilation issue for other platform.

PS: after reading the refmanual, I also split VALOEN and VALOVAL bit update as it is required.

So yes I think it is needed but I can split the patch to simplify the review.

Patrick