Re: [PATCH V2 0/1] usb: add HCD providers

[Peter Chen <hzpeterchen@gmail.com>]

On Wed, Jul 13, 2016 at 04:40:53PM +0200, Rafał Miłecki wrote:
> On 13 July 2016 at 15:50, Felipe Balbi <felipe.balbi@linux.intel.com> wrote:
> > Rafał Miłecki <zajec5@gmail.com> writes:
> >> On 13 July 2016 at 15:20, Felipe Balbi <felipe.balbi@linux.intel.com> wrote:
> >>> Rafał Miłecki <zajec5@gmail.com> writes:
> >>>> Hi again,
> >>>>
> >>>> This is my second try of getting HCD providers into usb subsystem.
> >>>>
> >>>> During discussion of V1 I realized there are about 26 drivers adding a
> >>>> single HCD and all of them would need to be modified. So instead I
> >>>> decided to put relevant code in usb_add_hcd. It checks if the HCD we
> >>>> register is a primary one and if so, it registers a proper provider.
> >>>>
> >>>> Please note that of_hcd_xlate_simple was also extended to allow getting
> >>>> shared HCD (which is used e.g. in case of XHCI).
> >>>>
> >>>> So now you can have something like:
> >>>>
> >>>> ohci: ohci@21000 {
> >>>>       #usb-cells = <0>;
> >>>>       compatible = "generic-ohci";
> >>>>       reg = <0x00001000 0x1000>;
> >>>>       interrupts = <GIC_SPI 1 IRQ_TYPE_LEVEL_HIGH>;
> >>>> };
> >>>>
> >>>> ehci: ehci@22000 {
> >>>>       #usb-cells = <0>;
> >>>>       compatible = "generic-ehci";
> >>>>       reg = <0x00002000 0x1000>;
> >>>>       interrupts = <GIC_SPI 2 IRQ_TYPE_LEVEL_HIGH>;
> >>>> };
> >>>>
> >>>> xhci: xhci@23000 {
> >>>>       #usb-cells = <1>;
> >>>>       compatible = "generic-xhci";
> >>>>       reg = <0x00003000 0x1000>;
> >>>>       interrupts = <GIC_SPI 3 IRQ_TYPE_LEVEL_HIGH>;
> >>>> };
> >>>>
> >>>> The last (second) patch is not supposed to be applied, it's used only as
> >>>> a proof and example of how providers can be used.
> >>>
> >>> nowhere here (or in previous patch) you clarify why exactly you need
> >>> this. What is your LED trigger supposed to do? Why can't it handle ports
> >>> changing number in different boots? Why do we need this at all? Why is
> >>> your code DT-specific?
> >>>
> >>> There are still too many 'unknowns' here.
> >>
> >> Are you sure you saw my reply to Peter's question?
> >> <CACna6rw6QOuY247qvDmO4mKrW3y4yXoeM3qr8SXAwn3CuYAMpw@mail.gmail.com>
> >> http://www.spinics.net/lists/linux-usb/msg143708.html
> >> http://marc.info/?l=linux-usb&m=146838735627093&w=2
> >>
> >> I think it should answer (some of?) your questions. Can you read it
> >> and see if it gets a bit clearer?
> >
> > well, all that says is that you're writing a LED trigger to toggle LED
> > when a USB device gets added to a specified port. I don't think you need
> > the actual port number for that. You should have a phandle to the actual
> > port, whatever its number is, or a phandle to the (root-)Hub and a port
> > number from that hub.
> >
> > The problem, really, is that DT descriptor of USB Hosts is very, very
> > minimal. Perhaps there's something more extensively defined from the
> > original Open Firmware USB Addendum.
> 
> Thanks for your effort and looking at this closely. You're right, I'm
> interested in referencing USB ports, but I'm using controller phandle
> (and then I specify ports manually).
> 
> Having each port described by DT would be helpful, it's just something
> I didn't find implemented, so I started looking for different ways. It
> seems I should have picked a different solution.
> 
> So should I work on describing USB ports in DT instead? This looks
> like a complex thing to describe, so I'd like to ask for some guidance
> first. What do you think about following schema/example?
> 
> ohci@1000 {
>         compatible = "generic-ohci";
>         reg = <0x00001000 0x1000>;
>         interrupts = <GIC_SPI 1 IRQ_TYPE_LEVEL_HIGH>;
> 
>         primary-hcd {
>                 ohci_port0: port@0 {
>                         reg = <0>;
>                 };
> 
>                 ohci_port1: port@1 {
>                         reg = <1>;
>                 };
>         }
> };
> 
> ehci@2000 {
>         compatible = "generic-ehci";
>         reg = <0x00002000 0x1000>;
>         interrupts = <GIC_SPI 2 IRQ_TYPE_LEVEL_HIGH>;
> 
>         primary-hcd {
>                 ehci_port0: port@0 {
>                         reg = <0>;
>                 };
> 
>                 ehci_port1: port@1 {
>                         reg = <1>;
>                 };
>         }
> };
> 
> xhci@3000 {
>         compatible = "generic-xhci";
>         reg = <0x00003000 0x1000>;
>         interrupts = <GIC_SPI 3 IRQ_TYPE_LEVEL_HIGH>;
> 
>         primary-hcd {
>         };
> 
>         shared-hcd {
>                 xhci_port0: port@0 {
>                         reg = <0>;
>                 };
>         }
> };
> 
> With such a DT struct, how could I query port for a Linux-assigned number?
> 
> For example with OHCI, EHCI and XHCI drivers compiled, Linux assigns
> number 4 to my XHCI's shared HCD's root hub:
> xhci-hcd 18023000.xhci: xHCI Host Controller
> xhci-hcd 18023000.xhci: new USB bus registered, assigned bus number 4
> hub 4-0:1.0: USB hub found
> hub 4-0:1.0: 1 port detected
> 
> If I disable OHCI and EHCI I get:
> xhci-hcd xhci-hcd.0: xHCI Host Controller
> xhci-hcd xhci-hcd.0: new USB bus registered, assigned bus number 2
> hub 2-0:1.0: USB hub found
> hub 2-0:1.0: 1 port detected
> 
> So I need my "usbport" trigger driver to be able to get "4-1" in the
> first case and "2-1" in the second case. I guess I should use
> &xhci_port0 but what then? How could I translate it into
> Linux-assigned numbering?
> 

For your current design, you need to fix shared hcd for xHCI problem,
since xHCI has two buses.

Below I supply another thought, please check if it is feasible.
In below design, you don't need to change any usb codes.

dts:

led_1 {
	led_gpio_1;
	usb_port = &ohci_port0, &ehci_port1;
}

led_2 {
	led_gpio_2;
	usb_port = &xhci_port0, &xhci_port1;
}

ohci@1000 {
        compatible = "generic-ohci";
        reg = <0x00001000 0x1000>;
        interrupts = <GIC_SPI 1 IRQ_TYPE_LEVEL_HIGH>;

	ohci_port0: port@0 {
		reg = <0>;
	};

	ohci_port1: port@1 {
		reg = <1>;
	};
};

ehci@2000 {
        compatible = "generic-ehci";
        reg = <0x00002000 0x1000>;
        interrupts = <GIC_SPI 2 IRQ_TYPE_LEVEL_HIGH>;

	ehci_port0: port@0 {
		reg = <0>;
	};

	ehci_port1: port@1 {
		reg = <1>;
	};
};

xhci@3000 {
        compatible = "generic-xhci";
        reg = <0x00003000 0x1000>;
        interrupts = <GIC_SPI 3 IRQ_TYPE_LEVEL_HIGH>;

	/* for xhci, port 0 - [N-1] is USB3, N - [M-1] is USB2/1.
	 * The port 0 and port N is the same physical port
	 */
	xhci_port0: port@0 {
		reg = <0>;
	};

	xhci_port1: port@1 {
		reg = <1>;
	};

};

At code, compare the usb_device's device_node at usbport_trig_notify
if it is at led_1's usb device list, light on it.

-- 

Best Regards,
Peter Chen