| Message ID | 20210210171040.684659-1-mka@chromium.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | USB: misc: Add onboard_usb_hub driver | expand |
On Wed, Feb 10, 2021 at 09:10:35AM -0800, Matthias Kaehlcke wrote: > This series adds the onboard_usb_hub_driver, the corresponding > device tree bindings and creation of onboard_usb_hub platform in > the xhci-plat driver during probe(). > > 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. It seems you are re-developing the power sequence drivers which perform exactly this. Peter Chen some time ago was bringing power sequence to USB devices, but I lost track where this ended up. Some of his (and my) very old work (2017...) can be found here: https://github.com/krzk/linux/tree/wip/odroid-u3-usb3503-pwrseq Instead of adding custom driver hiding some USB hub implementation, power sequence seems a generic solution. What if you need to power cycle other embedded USB device? Not a hub? I was not aware of previous discussions so maybe I am repeating someone. Best regards, Krzysztof
Hi Krzysztof, On Wed, Feb 10, 2021 at 10:04:51PM +0100, Krzysztof Kozlowski wrote: > On Wed, Feb 10, 2021 at 09:10:35AM -0800, Matthias Kaehlcke wrote: > > This series adds the onboard_usb_hub_driver, the corresponding > > device tree bindings and creation of onboard_usb_hub platform in > > the xhci-plat driver during probe(). > > > > 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. > > It seems you are re-developing the power sequence drivers which perform > exactly this. Peter Chen some time ago was bringing power sequence to > USB devices, but I lost track where this ended up. > > Some of his (and my) very old work (2017...) can be found here: > https://github.com/krzk/linux/tree/wip/odroid-u3-usb3503-pwrseq pwrseq was brought up in the discussion about this driver, but wasn't deemed suitable for this use case which might require more complex configurations: https://lore.kernel.org/patchwork/patch/1313000/#1512725 > Instead of adding custom driver hiding some USB hub implementation, > power sequence seems a generic solution. What if you need to power cycle > other embedded USB device? Not a hub? The driver could be extended to also cover other types of devices if desired. Maybe it should be called usb-pwrseq then, even though it's not directly related with the original pwrseq series.
Hi Matthias, On 2/10/21 6:10 PM, Matthias Kaehlcke wrote: > This series adds the onboard_usb_hub_driver, the corresponding > device tree bindings and creation of onboard_usb_hub platform in > the xhci-plat driver during probe(). > > 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. > Rob pointed me here at your series. http://lore.kernel.org/r/CAL_JsqJedhX6typpUKbnzV7CLK6UZVjq3CyG9iY_j5DLPqvVdw@mail.gmail.com And I have looked at RTS5411 datasheet and it looks very similar to Microchip usb5744 chip we use. Both have i2c/smbus and spi interfaces and also input clock. usb5744 has also external gpio reset. There are also usb3503 and others which should fit to this generic DT binding. Thanks, Michal That's why please keep me in the loop on v6 because I think
This series adds the onboard_usb_hub_driver, the corresponding device tree bindings and creation of onboard_usb_hub platform in the xhci-plat driver during probe(). 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. (no changes since v1) Matthias Kaehlcke (4): dt-bindings: usb: Add binding for discrete onboard USB hubs USB: misc: Add onboard_usb_hub driver usb: host: xhci-plat: Create platform device for onboard hubs in probe() arm64: dts: qcom: sc7180-trogdor: Add nodes for onboard USB hub .../bindings/usb/onboard_usb_hub.yaml | 49 +++ MAINTAINERS | 7 + .../boot/dts/qcom/sc7180-trogdor-lazor-r0.dts | 15 +- .../boot/dts/qcom/sc7180-trogdor-lazor-r1.dts | 11 +- .../arm64/boot/dts/qcom/sc7180-trogdor-r1.dts | 15 +- arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi | 18 +- drivers/usb/host/xhci-plat.c | 16 + drivers/usb/misc/Kconfig | 18 + drivers/usb/misc/Makefile | 1 + drivers/usb/misc/onboard_usb_hub.c | 409 ++++++++++++++++++ include/linux/usb/hcd.h | 2 + include/linux/usb/onboard_hub.h | 15 + 12 files changed, 542 insertions(+), 34 deletions(-) create mode 100644 Documentation/devicetree/bindings/usb/onboard_usb_hub.yaml create mode 100644 drivers/usb/misc/onboard_usb_hub.c create mode 100644 include/linux/usb/onboard_hub.h