On 9 September 2016 at 13:05, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > On Fri, Sep 09, 2016 at 05:34:40PM +0800, Peter Chen wrote: >> On Thu, Sep 08, 2016 at 06:08:24PM +0200, Rafał Miłecki wrote: >> > From: Rafał Miłecki <rafal@xxxxxxxxxx> >> > >> > This commit adds a new trigger responsible for turning on LED when USB >> > device gets connected to the selected USB port. This can can useful for >> > various home routers that have USB port(s) and a proper LED telling user >> > a device is connected. >> > >> > The trigger gets its documentation file but basically it just requires >> > enabling it and selecting USB ports (e.g. echo 1 > ports/usb1-1). >> > >> > There was a long discussion on design of this driver. Its current state >> > is a result of picking them most adjustable solution as others couldn't >> > handle all cases. >> > >> > 1) It wasn't possible for the driver to register separated trigger for >> > each USB port. Some physical USB ports are handled by more than one >> > controller and so by more than one USB port. E.g. USB 2.0 physical >> > port may be handled by OHCI's port and EHCI's port. >> > It's also not possible to assign more than 1 trigger to a single LED >> > and implementing such feature would be tricky due to syncing triggers >> > and sysfs conflicts with old triggers. >> > >> > 2) Another idea was to register trigger per USB hub. This wouldn't allow >> > handling devices with multiple USB LEDs and controllers (hubs) >> > controlling more than 1 physical port. It's common for hubs to have >> > few ports and each may have its own LED. >> > >> > This final trigger is highly flexible. It allows selecting any USB ports >> > for any LED. It was also modified (compared to the initial version) to >> > allow choosing ports rather than having user /guess/ proper names. It >> > was successfully tested on SmartRG SR400ac which has 3 USB LEDs, >> > 2 physical ports and 3 controllers. >> > >> > Another planned feature is support for LED reacting to the USB activity. >> > This can be implemented with another sysfs file for setting mode. The >> > default mode wouldn't change so there won't be ABI breakage and such >> > feature can be safely implemented later. >> > >> >> It has such driver at: drivers/usb/common/led.c > > Ugh, I thought I had seen something like this before... > > Rafał, can you just use this in-kernel code instead? I really don't think I can because of all the reasons I carefully listed in the commit message. Have you took a look at that simple driver? It does nothing I need. Its design doesn't allow implementing features I clearly listed in the commit message. -- Rafał -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
