[PATCH v2 0/3] USB: add generic onboard USB HUB driver

On Thu, Jan 07, 2016 at 08:18:02AM -0600, Rob Herring wrote:

On Tue, Jan 5, 2016 at 9:20 PM, Peter Chen [off-list ref] wrote:

quoted

On Tue, Jan 05, 2016 at 08:36:31AM -0600, Rob Herring wrote:

quoted

quoted

2. There are MFD USB devices, which includes several interfaces under
USB device,
like i2c, gpios, etc. Due to lack of device tree support, USB
class/device driver doesn't know
which kinds of interfaces are needed for this board.

Are you talking about a device hard wired on the same board or
something like GPIOs on FTDI chip which could be hot-plugged in any
host (including non-DT based)?

I talked about the case that the device hard wired on the board.
Hot-plug device's bus topology is unknown, we can't describe it
statically at dts.

Correct, upstream (the USB side) can't be described, but it is the
downstream side we care about describing.

quoted

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For the hotplug case, we will need a way to associate a DT overlay
with the USB device and there may not even be a base DT to map the
overlay into. In this case, the USB device's driver will need to load
the overlay and trigger enumerating the child devices. Anyway, this is
a separate issue from your problem.

Since both you and Alan agree with my problem should be fixed at
bootloader, I give the kernel solution up.

Surprising, no one ever seems to agree with that solution... There
will be people with this problem and unable to update their
bootloader.

Hi Rob, I noticed there are still some platform needs to this solution,
I would like to see if I can move this on, please review below dts
solution. In below case, there are two ports on the root hub, one is
USB HUB, the another is a USB wifi. Both of these devices need to have
power control before they can work.

At USB hcd driver, it will try to look-up all USB devices on this
controller, if the usb-pwr-ops is existed, it will try to get its
phandle, and do gpio and clock operations.

Optional properties:
- usb-pwr-ops: the power operations which need to do before this USB device
  can work.

Example:

/ {
	...

	hub_genesys_1_pwr_ops: hub_genesys_1_pwr_ops {
		compatible = "usb-pwrseq-simple";
		reset-gpios = <&gpio4 5 GPIO_ACTIVE_LOW>; /* hub reset pin */
		reset-duration-us = <10>;
		clocks = <&clks IMX6QDL_CLK_CKO>;
	};

	wifi_nxp_2_pwr_ops: wifi_nxp_2_pwr_ops {
		compatible = "usb-pwrseq-simple";
		reset-gpios = <&gpio4 6 GPIO_ACTIVE_LOW>, /* wifi_rst */
				<&gpio4 7 GPIO_ACTIVE_LOW>; /* wifi_en */
		reset-duration-us = <10>;
		clocks = <&clks IMX6QDL_CLK_CKO1>;
	};

	...
};

&usb1 {
	status = "okay";

	#address-cells = <1>;
	#size-cells = <0>;

	hub: genesys at 1 {
		compatible = "usb5e3,608";
		reg = <1>;
		usb-pwr-ops = <&hub_genesys_1_pwr_ops>
	};

	wifi: nxp at 2 {
		compatible = "usb5e3,608";
		reg = <2>;
		usb-pwr-ops = <&wifi_nxp_2_pwr_ops>
	};
}

-- 

Best Regards,
Peter Chen