Date:   Tue, 17 May 2022 13:06:29 +0200
From:   Michal Simek <michal.simek@...inx.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Michal Simek <michal.simek@...inx.com>
CC:     Matthias Kaehlcke <mka@...omium.org>,
        Doug Anderson <dianders@...omium.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>,
        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



On 5/17/22 12:43, Greg Kroah-Hartman wrote:
> On Tue, May 17, 2022 at 12:36:03PM +0200, Michal Simek wrote:
>> Hi Greg,
>>
>> On 4/26/22 14:01, Greg Kroah-Hartman wrote:
>>> On Thu, Apr 21, 2022 at 11:13:08AM -0700, Matthias Kaehlcke wrote:
>>>> 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.
>>>
>>> After 21 different versions, there's nothing left for me to object to,
>>> so I'll go queue it up.  Thanks for sticking with it.
>>
>> I just checked linux-next and this series is still not there. Are you going
>> to merge it or are you waiting for v22?
> 
> It was merged, and I had to revert it based on reports of problems with
> it.  See the thread here:
> 	https://lore.kernel.org/r/20220502210728.0b36f3cd@canb.auug.org.au
> for details.

Matthias: Are you going to send v22 version?

Thanks,
Michal

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