[PATCH v4 0/3] usb: dwc3: parkmode_disable_ss_quirk on DWC3 controller

[Neil Armstrong]

In certain circumstances, the XHCI SuperSpeed instance in park mode
can fail to recover, thus on Amlogic G12A/G12B/SM1 SoCs when there is high
load on the single XHCI SuperSpeed instance, the controller can crash like:
xhci-hcd xhci-hcd.0.auto: xHCI host not responding to stop endpoint command.
xhci-hcd xhci-hcd.0.auto: Host halt failed, -110
xhci-hcd xhci-hcd.0.auto: xHCI host controller not responding, assume dead
xhci-hcd xhci-hcd.0.auto: xHCI host not responding to stop endpoint command.
hub 2-1.1:1.0: hub_ext_port_status failed (err = -22)
xhci-hcd xhci-hcd.0.auto: HC died; cleaning up
usb 2-1.1-port1: cannot reset (err = -22)

Setting the PARKMODE_DISABLE_SS bit in the DWC3_USB3_GUCTL1 mitigates
the issue. The bit is described as :
"When this bit is set to '1' all SS bus instances in park mode are disabled"

The bug has been reproduced by Jun Li <lijun.kernel@xxxxxxxxx> and confirmed
by Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx> with the explanation:
> The GUCTL1.PARKMODE_DISABLE_SS is only available in dwc_usb3 controller 
> running in host mode. This should not be set for other IPs.
> This can be disabled by default based on IP, but I recommend to have a 
> property to enable this feature for devices that need this.

Changes since v3 at [3]:
- fixed patch 3 subject

Changes since v2 at [2]:
- rebased on v5.6-rc2

Changes since v1 at [1]:
- added rob review tag
- added Thinh Nguyen in commit log

[1] https://lore.kernel.org/linux-usb/20191014141718.22603-1-narmstrong@xxxxxxxxxxxx
[2] https://lore.kernel.org/linux-usb/20200109101535.26812-1-narmstrong@xxxxxxxxxxxx
[3] https://lore.kernel.org/linux-usb/20200219141817.24521-1-narmstrong@xxxxxxxxxxxx

Neil Armstrong (3):
  doc: dt: bindings: usb: dwc3: Update entries for disabling SS
    instances in park mode
  usb: dwc3: core: add support for disabling SS instances in park mode
  arm64: dts: g12-common: add parkmode_disable_ss_quirk on DWC3
    controller

 Documentation/devicetree/bindings/usb/dwc3.txt    | 2 ++
 arch/arm64/boot/dts/amlogic/meson-g12-common.dtsi | 1 +
 drivers/usb/dwc3/core.c                           | 5 +++++
 drivers/usb/dwc3/core.h                           | 4 ++++
 4 files changed, 12 insertions(+)

-- 
2.22.0