Message-ID: <YmGetA6Huz4Sj/RL@google.com>
Date:   Thu, 21 Apr 2022 11:13:08 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Doug Anderson <dianders@...omium.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>,
        Linux USB List <linux-usb@...r.kernel.org>,
        Ravi Chandra Sadineni <ravisadineni@...omium.org>,
        Roger Quadros <rogerq@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Bastien Nocera <hadess@...ess.net>,
        Michal Simek <michal.simek@...inx.com>,
        Stephen Boyd <swboyd@...omium.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Peter Chen <peter.chen@...nel.org>,
        Guo Zhengkui <guozhengkui@...o.com>,
        Kishon Vijay Abraham I <kishon@...com>,
        Li Jun <jun.li@....com>, Peter Chen <peter.chen@....com>,
        Thinh Nguyen <Thinh.Nguyen@...opsys.com>
Subject: Re: [PATCH v21 0/3] usb: misc: Add onboard_usb_hub driver

Hi,

On Thu, Apr 07, 2022 at 12:41:22PM -0700, Doug Anderson wrote:
> Hi,
> 
> On Thu, Feb 17, 2022 at 10:43 AM Matthias Kaehlcke <mka@...omium.org> wrote:
> >
> > This series adds:
> > - the onboard_usb_hub_driver
> > - glue in the generic HCD code to create and destroy the
> >   onboard_usb_hub platform devices if needed
> > - 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 v21:
> > - dropped patch 'driver core: Export device_is_bound()'
> > - refactored _find_onboard_hub()
> > - removed 'onboard_hub_dev' symlinks from USB devices
> > - dropped patch 'arm64: dts: qcom: sc7180-trogdor: Add nodes for onboard USB hub'
> >   (will be sent separately)
> > - rebased series on v5.17-rc4
> >
> > Changes in v20:
> > - addressed review comments from Stephen
> > - changed DT node names for hubs
> >
> > Changes in v19:
> > - added VID:PID pairs and compatible strings for RTS5414 hub
> > - updated comments with RTS5411 USB versions to reflect those
> >   reported/supported by the hub
> > - rebased series on v5.16
> >
> > Changes in v18:
> > - introduced hidden Kconfig option to align module vs. builtin
> >   choice with CONFIG_USB (thanks Doug!)
> > - added patch 'driver core: Export device_is_bound()'
> > - also adjust device tree of pompom rev1
> > - dropped the following patches, which aren't needed anymore by this
> >   series (though they might still be useful on their own):
> >   - usb: Specify dependencies on USB_XHCI_PLATFORM with 'depends on'
> >   - arm64: defconfig: Explicitly enable USB_XHCI_PLATFORM
> >   - ARM: configs: Explicitly enable USB_XHCI_PLATFORM where needed
> >
> > Changes in v17:
> > - rebased on top of v5.16-rc1
> > - moved creation of onboard_hub platform devices from xhci_platform
> >   to the generic HCD code
> > - addressed review comments for the onboard_hub driver
> > - moved Kconfig/defconfig changes to the end of the series. The
> >   onboard_hub driver doesn't depend on XHCI_PLATFORM anymore,
> >   hence these changes aren't really required for the driver, but
> >   they still seem to be a worthwhile improvement
> >
> > Changes in v16:
> > - added patch 'ARM: configs: Explicitly enable USB_XHCI_PLATFORM
> >   where needed' to keep arm32 defconfigs effectively unchanged
> >
> > 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 (3):
> >   of/platform: Add stubs for of_platform_device_create/destroy()
> >   usb: misc: Add onboard_usb_hub driver
> >   usb: core: hcd: Create platform devices for onboard hubs in probe()
> >
> >  .../sysfs-bus-platform-onboard-usb-hub        |   8 +
> >  MAINTAINERS                                   |   7 +
> >  drivers/usb/core/hcd.c                        |   6 +
> >  drivers/usb/misc/Kconfig                      |  23 +
> >  drivers/usb/misc/Makefile                     |   1 +
> >  drivers/usb/misc/onboard_usb_hub.c            | 510 ++++++++++++++++++
> >  include/linux/of_platform.h                   |  22 +-
> >  include/linux/usb/hcd.h                       |   1 +
> >  include/linux/usb/onboard_hub.h               |  18 +
> >  9 files changed, 592 insertions(+), 4 deletions(-)
> >  create mode 100644 Documentation/ABI/testing/sysfs-bus-platform-onboard-usb-hub
> >  create mode 100644 drivers/usb/misc/onboard_usb_hub.c
> >  create mode 100644 include/linux/usb/onboard_hub.h
> 
> With v5.18-rc1 out the door, I wonder if it's a good time to look at
> this series again. Are there any hidden blockers that it's waiting
> for?

Greg, please let me know if any further changes are needed or if this
series can be landed.

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