Re: [PATCH v15 0/6] usb: misc: Add onboard_usb_hub driver

[Matthias Kaehlcke <mka@chromium.org>]

Hi Roger,

On Wed, Aug 11, 2021 at 03:56:15PM +0300, Roger Quadros wrote:
> 
> 
> On 11/08/2021 15:38, Roger Quadros wrote:
> > Hi Matthias,
> > 
> > On 09/08/2021 18:49, Matthias Kaehlcke wrote:
> >> Hi Greg,
> >>
> >> Just wanted to check if this series is still on your radar. Is
> >> there anything that blocks it from landing (further ACKs, ...)?
> >>
> >> Thanks
> >>
> >> Matthias
> >>
> >> On Mon, Jul 26, 2021 at 05:41:12PM -0700, Matthias Kaehlcke wrote:
> >>> This series adds:
> >>> - the onboard_usb_hub_driver
> >>> - glue in the xhci-plat driver to create and destroy the
> >>>   onboard_usb_hub platform devices if needed
> >>> - a device tree binding for the Realtek RTS5411 USB hub controller
> >>> - device tree changes that add RTS5411 entries for the QCA SC7180
> >>>   based boards trogdor and lazor
> >>> - a couple of stubs for platform device functions to avoid
> >>>   unresolved symbols with certain kernel configs
> >>>
> >>> The main issue the driver addresses is that a USB hub needs to be
> >>> powered before it can be discovered. For discrete onboard hubs (an
> >>> example for such a hub is the Realtek RTS5411) this is often solved
> >>> by supplying the hub with an 'always-on' regulator, which is kind
> >>> of a hack. Some onboard hubs may require further initialization
> >>> steps, like changing the state of a GPIO or enabling a clock, which
> >>> requires even more hacks. This driver creates a platform device
> >>> representing the hub which performs the necessary initialization.
> >>> Currently it only supports switching on a single regulator, support
> >>> for multiple regulators or other actions can be added as needed.
> >>> Different initialization sequences can be supported based on the
> >>> compatible string.
> >>>
> >>> Besides performing the initialization the driver can be configured
> >>> to power the hub off during system suspend. This can help to extend
> >>> battery life on battery powered devices which have no requirements
> >>> to keep the hub powered during suspend. The driver can also be
> >>> configured to leave the hub powered when a wakeup capable USB device
> >>> is connected when suspending, and power it off otherwise.
> >>>
> >>> Changes in v15:
> >>> - adjusted dependencies of USB_DWC3_CORE to make sure it can only
> >>>   be enabled when at least one of USB_DWC3_HOST, USB_DWC3_GADGET
> >>>   or USB_DWC3_DUAL_ROLE is selectable
> >>>
> >>> Changes in v14:
> >>> - rebased on top of v5.14-rc1
> >>> - dropped DT binding patch which landed in v5.13
> >>>
> >>> Changes in v13:
> >>> - added patch "usb: Specify dependency on USB_XHCI_PLATFORM with
> >>>   'depends on'" to the series to avoid Kconfig conflicts
> >>> - added patch "arm64: defconfig: Explicitly enable USB_XHCI_PLATFORM"
> >>>   to the series to keep effective defconfig unchanged
> >>>
> >>> Changes in v12:
> >>> - onboard_hub driver: use IS_ENABLED(CONFIG_USB_ONBOARD_HUB_MODULE)
> >>>   in onboard_hub.h to also check for the driver built as module
> >>> - onboard_hub_driver: include onboard_hub.h again to make sure there
> >>>   are prototype declarations for the public functions
> >>>
> >>> Changes in v11:
> >>> - support multiple onboard hubs connected to the same parent
> >>> - don't include ‘onboard_hub.h’ from the onboard hub driver
> >>>
> >>> Changes in v10:
> >>> - always use of_is_onboard_usb_hub() stub unless ONBOARD_USB_HUB=y/m
> >>> - keep 'regulator-boot-on' property for pp3300_hub
> >>>
> >>> Changes in v9:
> >>> - added dependency on ONBOARD_USB_HUB (or !!ONBOARD_USB_HUB) to
> >>>   USB_PLATFORM_XHCI
> >>>
> >>> Changes in v7:
> >>> - updated DT binding
> >>> - series rebased on qcom/arm64-for-5.13
> >>>
> >>> Changes in v6:
> >>> - updated summary
> >>>
> >>> Changes in v5:
> >>> - cover letter added
> >>>
> >>> Matthias Kaehlcke (6):
> >>>   usb: misc: Add onboard_usb_hub driver
> >>>   of/platform: Add stubs for of_platform_device_create/destroy()
> >>>   arm64: defconfig: Explicitly enable USB_XHCI_PLATFORM
> >>>   usb: Specify dependencies on USB_XHCI_PLATFORM with 'depends on'
> >>>   usb: host: xhci-plat: Create platform device for onboard hubs in
> >>>     probe()
> >>>   arm64: dts: qcom: sc7180-trogdor: Add nodes for onboard USB hub
> >>>
> >>>  .../sysfs-bus-platform-onboard-usb-hub        |   8 +
> >>>  MAINTAINERS                                   |   7 +
> >>>  .../boot/dts/qcom/sc7180-trogdor-lazor-r0.dts |  19 +-
> >>>  .../boot/dts/qcom/sc7180-trogdor-lazor-r1.dts |  12 +-
> >>>  .../arm64/boot/dts/qcom/sc7180-trogdor-r1.dts |  19 +-
> >>>  arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi  |  19 +-
> >>>  arch/arm64/configs/defconfig                  |   1 +
> >>>  drivers/usb/cdns3/Kconfig                     |   2 +-
> >>>  drivers/usb/dwc3/Kconfig                      |   5 +-
> >>>  drivers/usb/host/Kconfig                      |   5 +-
> > 
> > These Kconfig changes are causing the resulting .config to be different.
> > For example, if I start with omap2plus_defconfig, the resulting .config
> > before and after your series is different as shown below
> > 
> > :/work/linux$ diff /tmp/.config .config
> > 1902d1901
> > < # CONFIG_HISI_HIKEY_USB is not set
> > 4992c4991
> > < CONFIG_USB_XHCI_PLATFORM=m
> > ---
> >> # CONFIG_USB_XHCI_PLATFORM is not set
> > 5073,5075c5072
> > < # CONFIG_USB_DWC3_HOST is not set
> > < # CONFIG_USB_DWC3_GADGET is not set
> > < CONFIG_USB_DWC3_DUAL_ROLE=y
> > ---
> >> CONFIG_USB_DWC3_GADGET=y
> > 5173a5171
> >> # CONFIG_USB_ONBOARD_HUB is not set
> > 5285c5283
> > < CONFIG_USB_ROLE_SWITCH=m
> > ---
> >> # CONFIG_USB_ROLE_SWITCH is not set
> > 
> > I would expect the same issues for multi_v7_defconfig and multi_v8_defconfig as well.
> 
> Sorry I meant defconfig for arm64, not multi_v8_defconfig.
> 
> I checked that for arm64 defconfig it is ok.
> 
> > I'm ok to update the relevant defconfigs files so that the resulting .config is identical to
> > before your series. Thanks!
> 
> With the below patch you can fix it for omap2plus_defconfig and multi_v7_defconfig.
> 
> diff --git a/arch/arm/configs/multi_v7_defconfig b/arch/arm/configs/multi_v7_defconfig
> index d9abaae118dd..8c175ab37377 100644
> --- a/arch/arm/configs/multi_v7_defconfig
> +++ b/arch/arm/configs/multi_v7_defconfig
> @@ -787,6 +787,7 @@ CONFIG_SND_AUDIO_GRAPH_CARD=m
>  CONFIG_USB=y
>  CONFIG_USB_OTG=y
>  CONFIG_USB_XHCI_HCD=y
> +CONFIG_USB_XHCI_PLATFORM=y
>  CONFIG_USB_XHCI_MVEBU=y
>  CONFIG_USB_XHCI_TEGRA=m
>  CONFIG_USB_EHCI_HCD=y
> diff --git a/arch/arm/configs/omap2plus_defconfig b/arch/arm/configs/omap2plus_defconfig
> index 2ac2418084ab..a015fb04fa25 100644
> --- a/arch/arm/configs/omap2plus_defconfig
> +++ b/arch/arm/configs/omap2plus_defconfig
> @@ -562,6 +562,7 @@ CONFIG_USB=m
>  CONFIG_USB_ANNOUNCE_NEW_DEVICES=y
>  CONFIG_USB_MON=m
>  CONFIG_USB_XHCI_HCD=m
> +CONFIG_USB_XHCI_PLATFORM=m
>  CONFIG_USB_EHCI_HCD=m
>  CONFIG_USB_OHCI_HCD=m
>  CONFIG_USB_ACM=m

Thanks for testing!

I completely forgot that arm32 has all these different defconfigs.

While trying to adjust qcom_defconfig I came across something that confuses
me. The original defconfig results in:

# CONFIG_USB_XHCI_HCD is not set
CONFIG_USB_DWC3_DUAL_ROLE=y

My assumption was that xHCI support is need for dwc3 dual mode (which is
made explicit by https://lore.kernel.org/patchwork/patch/1468240/), is
that incorrect? Maybe without xHCI support the controller can still
operate in USB 2.0 dual role mode?