DT on s3c24xx
linus.walleij at linaro.org
Thu Dec 18 06:53:14 PST 2014
On Thu, Dec 18, 2014 at 9:34 AM, Vasily Khoruzhick <anarsoul at gmail.com> wrote:
> Can I change pin function after gpio was requested? In low-power state
> (i.e. when display is disabled) it's gpio driving some level,
> and in active state it's some LCD controller pin (don't remember which
> one exactly)
Please read the section named "GPIO mode pitfalls" in
Documentation/pinctrl.txt very closely.
- You can use the GPIO and pin control interface to the same
hardware in parallel. There is no blocking this since there
is hardware out that that actually allow this. NOT
- If the "GPIO mode" mentioned is only about e.g. grounding
the pins in a low power state and then not really about using
them as GPIO, extend the pin controller to be able to e.g.
ground the pins with PIN_CONFIG_OUTPUT or
PIN_CONFIG_LOW_POWER_MODE if you use
If the usecase is low power, the latter approach is recommended.
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