Message-ID: <YRa65ZWzkB5OLpPm@google.com>
Date:   Fri, 13 Aug 2021 11:33:09 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Roger Quadros <rogerq@...nel.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Alan Stern <stern@...land.harvard.edu>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Mathias Nyman <mathias.nyman@...el.com>,
        Felipe Balbi <balbi@...nel.org>,
        Bastien Nocera <hadess@...ess.net>,
        Peter Chen <peter.chen@...nel.org>, devicetree@...r.kernel.org,
        Michal Simek <michal.simek@...inx.com>,
        linux-kernel@...r.kernel.org,
        Douglas Anderson <dianders@...omium.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        linux-usb@...r.kernel.org,
        Ravi Chandra Sadineni <ravisadineni@...omium.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Al Cooper <alcooperx@...il.com>,
        Andrey Zhizhikin <andrey.zhizhikin@...ca-geosystems.com>,
        Andy Gross <agross@...nel.org>,
        Aswath Govindraju <a-govindraju@...com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Dmitry Osipenko <digetx@...il.com>,
        Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        Fabio Estevam <festevam@...il.com>,
        Guido Günther <agx@...xcpu.org>,
        Jagan Teki <jagan@...rulasolutions.com>,
        Nishanth Menon <nm@...com>,
        Pawel Laszczak <pawell@...ence.com>,
        Shawn Guo <shawnguo@...nel.org>, Vinod Koul <vkoul@...nel.org>,
        Will Deacon <will@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH v15 0/6] usb: misc: Add onboard_usb_hub driver

On Fri, Aug 13, 2021 at 09:35:53AM +0300, Roger Quadros wrote:
> Hi Matthias,
> 
> On 12/08/2021 20:08, Matthias Kaehlcke wrote:
> > 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
> 
> The original Kconfig was:
> 
> > config USB_DWC3_DUAL_ROLE
> >         bool "Dual Role mode"
> >         depends on ((USB=y || USB=USB_DWC3) && (USB_GADGET=y || USB_GADGET=USB_DWC3))
> >         depends on (EXTCON=y || EXTCON=USB_DWC3)
> 
> Which means USB_DWC3_DUAL_ROLE can be enabled even without CONFIG_USB_XHCI_HCD.
> 
> All the dual role code does is add/remove the host/gadget controller platform devices.
> It doesn't care whether there is a driver for it or not.
> i.e. there is no build dependency on CONFIG_USB_XHCI_HCD.
> 
> > 
> > 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?
> > 
> 
> Without xHCI support the host functionality will not work at all on dwc3 dual role.
> So I think your Kconfig changes for USB_DWC3_DUAL_ROLE to depend on USB_XHCI_PLATFORM
> are correct.

Thanks for the clarification!

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