Messages in this thread | | | Date | Mon, 24 Oct 2011 09:26:38 +0200 | Subject | Re: [PATCH] drivers: create a pin control subsystem v8 | From | Linus Walleij <> |
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On Sat, Oct 22, 2011 at 7:44 PM, Mike Frysinger <vapier.adi@gmail.com> wrote: > On Tue, Oct 4, 2011 at 16:35, Grant Likely wrote: >> On Sat, Oct 01, 2011 at 12:39:21PM +0200, Linus Walleij wrote: >>> 2011/9/30 Grant Likely: >>> > I'm not convinced that the sysfs approach is >>> > actually the right interface here (I'm certainly not a fan of the gpio >>> > sysfs i/f), and I'd rather not be putting in unneeded stuff until the >>> > userspace i/f is hammered out. >>> >>> Actually, thinking about it I cannot see what would be wrong >>> with /dev/gpio0 & friends in the first place. >>> >>> Using sysfs as swiss army knife for custom I/O does not >>> seem like it would be long-term viable so thanks for this >>> observation, and I think we need /dev/gpio* put on some >>> mental roadmap somewhere. >> >> Agreed. I don't want to be in the situation we are now with GPIO, >> where every time I look at the sysfs interface I shudder. > > the problem with that is it doesn't scale. if i have a device with > over 150 GPIOs on the SoC itself (obviously GPIO expanders can make > that much bigger), i don't want to see 150+ device nodes in /dev/. > that's a pretty big waste. sysfs only allocates/frees resources when > userspace actually wants to utilize a GPIO.
I was more thinking along the lines of one device per GPIO controller, then you ioctl() to ask /dev/gpio0 how many pins it has or so.
Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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