Messages in this thread | | | From | Linus Walleij <> | Date | Mon, 1 Oct 2018 11:43:55 +0200 | Subject | Re: [PATCH 0/2] USB: serial: gpio line-name fix and FT232R CBUS gpio support |
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On Sun, Sep 30, 2018 at 2:29 PM Johan Hovold <johan@kernel.org> wrote:
> Turns out gpiolib still doesn't like having non-unique line names, so > drop the line names from the recently added FTX cbus gpio > implementation before adding support also for FT232R.
Oh.
> Linus, we finally got around to adding gpio support for FTDI devices; > see commit > > ba93cc7da896 ("USB: serial: ftdi_sio: implement GPIO support for FT-X devices") > > in my usb-next branch (and linux-next).
This is good news, I think it's a pretty neat way for people to get a few inexpensive GPIOs from their serial adapters.
> The gpiolib warnings and inability to use the legacy sysfs interface > prevents us from setting the line names however as someone is bound to > plugin more than one of these devices at some point. I think we > discussed this issue with the name space and hotpluggable devices a few > years ago, but looks like this topic may need to be revisited.
Hm I guess the right long-term fix is to allow per-gpiochip unique names rather than enforcing globally unique names.
The idea is to make it possible for userspace to look up a GPIO on a chip by name, so if the gpiochip has a unique name, and the line name is unique on that chip it should be good enough.
Yours, Linus Walleij
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