From: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
To: Matthias Kaehlcke <mka@chromium.org>
Cc: "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Alan Stern" <stern@rowland.harvard.edu>,
"Rob Herring" <robh+dt@kernel.org>,
"Frank Rowand" <frowand.list@gmail.com>,
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"Felipe Balbi" <balbi@kernel.org>,
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"Peter Chen" <peter.chen@kernel.org>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>,
"Michal Simek" <michal.simek@xilinx.com>,
"open list" <linux-kernel@vger.kernel.org>,
"Douglas Anderson" <dianders@chromium.org>,
"Krzysztof Kozlowski" <krzk@kernel.org>,
linux-usb@vger.kernel.org,
"Ravi Chandra Sadineni" <ravisadineni@chromium.org>,
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"Al Cooper" <alcooperx@gmail.com>,
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<linux-arm-msm@vger.kernel.org>
Subject: Re: [PATCH v15 0/6] usb: misc: Add onboard_usb_hub driver
Date: Tue, 19 Oct 2021 19:24:41 +0300 [thread overview]
Message-ID: <CAA8EJpq55e+fk9oDi8+JXDWiPcXDXK5oz1DL5eqfx+FkT-xhnw@mail.gmail.com> (raw)
In-Reply-To: <20210727004118.2583774-1-mka@chromium.org>
On Tue, 27 Jul 2021 at 03:41, Matthias Kaehlcke <mka@chromium.org> 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.
I have the feeling that you might want to check if you can use pwrseq
subsystem being proposed at
https://lore.kernel.org/linux-arm-msm/20211006035407.1147909-1-dmitry.baryshkov@linaro.org/.
It has been created for exactly the same reason of handling complex
power up/down requirements in a bus-neutral way. So instead of
creating an onboard-usb-hub, you might want to populate the hub node
with the reference to pwrseq device and make usb core call into
pwrseq. How does that sound to you?
>
> 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.
--
With best wishes
Dmitry
next prev parent reply other threads:[~2021-10-19 16:24 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-27 0:41 [PATCH v15 0/6] usb: misc: Add onboard_usb_hub driver Matthias Kaehlcke
2021-07-27 0:41 ` [PATCH v15 1/6] " Matthias Kaehlcke
2021-07-27 0:41 ` [PATCH v15 2/6] of/platform: Add stubs for of_platform_device_create/destroy() Matthias Kaehlcke
2021-07-27 0:41 ` [PATCH v15 3/6] arm64: defconfig: Explicitly enable USB_XHCI_PLATFORM Matthias Kaehlcke
2021-07-27 0:41 ` [PATCH v15 4/6] usb: Specify dependencies on USB_XHCI_PLATFORM with 'depends on' Matthias Kaehlcke
2021-07-27 0:41 ` [PATCH v15 5/6] usb: host: xhci-plat: Create platform device for onboard hubs in probe() Matthias Kaehlcke
2021-07-27 0:41 ` [PATCH v15 6/6] arm64: dts: qcom: sc7180-trogdor: Add nodes for onboard USB hub Matthias Kaehlcke
2021-08-09 15:49 ` [PATCH v15 0/6] usb: misc: Add onboard_usb_hub driver Matthias Kaehlcke
2021-08-11 12:38 ` Roger Quadros
2021-08-11 12:56 ` Roger Quadros
2021-08-12 17:08 ` Matthias Kaehlcke
2021-08-13 6:35 ` Roger Quadros
2021-08-13 18:33 ` Matthias Kaehlcke
2021-10-19 16:24 ` Dmitry Baryshkov [this message]
2021-10-19 22:54 ` Matthias Kaehlcke
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