On 13 July 2016 at 10:02, Peter Chen <hzpeterchen@xxxxxxxxx> wrote: > On Wed, Jul 13, 2016 at 07:21:09AM +0200, Rafał Miłecki wrote: >> On 13 July 2016 at 06:51, Peter Chen <hzpeterchen@xxxxxxxxx> wrote: >> > On Tue, Jul 12, 2016 at 02:35:18PM +0200, Rafał Miłecki wrote: >> >> I was working on an "usbport" LED trigger driver and specifying its >> >> default state in DT. I realized I can't really determine numbering of >> >> USB ports on any device as it depends on compiled drivers and the >> >> loading orders. >> >> >> >> It means that my physical USB port can be e.g. 1-1 or 2-1 depending on >> >> my current config/setup. I needed a way to specify a particular HCD in >> >> DT and then hardcode port number (as this part doesn't change). >> >> >> > >> > I have a question: >> > >> > What does your "usbport" LED trigger for? What kinds of information >> > you would like to show on LED? >> >> It's a trigger that turns on LED whenever USB device appears at >> specified USB port. There are plenty of home routers that have USB >> labeled LED(s). To support them nicely, first of all we need a trigger >> that will watch for USB subsystem events. Secondly we need a way to >> setup its initial state correctly as most users don't want to play >> with sysfs on their own. >> >> I sent usbport trigger in: >> [PATCH] leds: trigger: Introduce an USB port trigger >> <1468239883-22695-1-git-send-email-zajec5@xxxxxxxxx> >> https://lkml.org/lkml/2016/7/11/305 >> You may read commit message and ledtrig-usbport.txt for more details. >> > > Well, it is an interesting use case. You can try to add provider (un)register > at hub driver (drivers/usb/core/hub.c) instead of each platform drivers, you > could refer my USB pwrseq as an example[1]. That was my initial plan, but then I realized we can have more complex cases with few HCDs per single device (and device_node). Take a look at dummy_hcd.c, xhci-mtk.c and xhci-plat.c. All of them register two HCDs: a shared one and primary one. In above drivers I planned to have custom xlate function with support for an extra argument. I was thinking about something like: usb-controllers = <&ohci>, <&ehci>, <&xhci USB_HCD_SHARED>; Now you made me look closer at controller drivers, I'm not so sure what is the best way for this. We have ~65 drivers registering only one HCD and ~26 of them use DT. We should modify at least those ~26 ones to register a provider. So maybe it's indeed better to add providers in a generic way, probably just inside usb_add_hcd. We could make generic xlate function aware of primary and shared HCDs. Hopefully there won't be way more complicate cases in the future, like a single controller driver registering 3, 4 or more HCDs. If that ever happens, we can always modify usb_add_hcd to somehow tell it to don't register providers in such cases. > For roothub, you can get the busnum through comparing controller's of_node, for > internal hub, you can get hub's dev name like (1-1) through comparing > its of_node (you need to describe your hard-wired hub on dts). I'm not really sure what do you mean here. I believe my of_hcd_get_from_provider already does compare controller's of_node? When working with internal hubs I never meant to reference them in DT. I meant to reference root hub only and then hardcode the rest of "path". For example my old BCM4706 device (MIPS supported by bcm47xx without DT) has internal 05e3:0608 Genesys Logic, Inc. USB-2.0 4-Port HUB connected to the 1-1. It has 2 physical USB connectors, if I connect USB device to the "upper" one it appears as 1-1.1, if I connect to the "lower" it appears as 1-1.2. In such case (if bcm47xx was using DT) I'd only need reference to "1" root hub bus number and I could hardcode "1.1" and "1.2" in DT. > Two more questions: > > - How to support the USB device on the port when boots up? It's not supported by my usbport trigger driver yet. I'll probably support it by calling usb_find_device_by_name whenever a new entry gets added to the list of monitored ports. > - Any cases we need to add mapping using new_port_store, the user may > not know bus number for physical port. Initially I implemented new_port_store for my testing purposes but I think it may be useful for platforms without DT. It would allow some user space scripts to add proper entries. -- Rafał -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
