[PATCH v2 0/2] usb: dwc2: fix USB peripheral role in dual-role mode on PX30

[Quentin Schulz]

On Theobroma Ringneck SoM, USB peripheral role when in dual-role mode does not
work and displays the following error message:
dwc2 ff300000.usb: dwc2_core_reset: HANG! Soft Reset timeout GRSTCTL_CSFTRST

The USB sniffer shows nothing and dumping the host registers is stuck on
HCDMA(0) register.

Note that for some reason it works "fine" on PX30-EVB (there's another issue but
not related to/fixed in this patch series).

Since there's no documentation available for this IP, this patch series is
basically just slightly adapted downstream BSP vendor kernel patches and I
cannot unfortunately give more information than what I have.

This patch series was tested on Theobroma Ringneck SoM on Haikou devkit and PX30
EVB. It fixes Ringneck support and does not break PX30-EVB's.

For reference, the content of those commits can be found in tag
linux-5.10-gen-rkr1, and the following commits have been used:
964d50060bf53a8defd1fc561b9261424f25ddad
ad81c375602819a538ad68d979906c05663046e2
6e6adab8f735bc4fe27a67bdc3144d8fa89250d4
7c3a4e60247fd7f7b04d95d15cb12c63a5c20408

Note that Rockchip kernel called a slightly different implementation of
__dwc2_lowlevel_hw_enable instead of dwc2_lowlevel_hw_enable but it seemed more
right to me to call dwc2_lowlevel_hw_enable as done for the forced peripheral
mode.

Note that it is still not flawlessly working but the support is improved
(somewhat working vs not working at all).

To: Minas Harutyunyan <hminas@xxxxxxxxxxxx>
To: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: linux-usb@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: Bin Yang <yangbin@xxxxxxxxxxxxxx>
Signed-off-by: Quentin Schulz <quentin.schulz@xxxxxxxxxxxxxxxxxxxxx>
---
Changes in v2:
- add "shadow" variable for HCD skip_phy_initialization so that it can be
  configured on a per-platform basis,
- Patch 1 and Patch 2 of the v1 are already in linux-next next-20221216, so removed from this series,
- Link to v1: https://lore.kernel.org/r/20221206-dwc2-gadget-dual-role-v1-0-36515e1092cd@xxxxxxxxxxxxxxxxxxxxx

---
Quentin Schulz (2):
      usb: dwc2: allow platforms to prevent core phy initialisation
      usb: dwc2: prevent core PHY initialization on Rockchip

 drivers/usb/dwc2/core.h   | 6 ++++++
 drivers/usb/dwc2/hcd.c    | 2 ++
 drivers/usb/dwc2/params.c | 1 +
 3 files changed, 9 insertions(+)
---
base-commit: ca39c4daa6f7f770b1329ffb46f1e4a6bcc3f291
change-id: 20221206-dwc2-gadget-dual-role-aac67e6d42fd

Best regards,
-- 
Quentin Schulz <quentin.schulz@xxxxxxxxxxxxxxxxxxxxx>