[Letux-kernel] [PATCH pre-upstream RFC] ARM: dts: omap3-gta04: add pulldown/up settings for twl4030 gpio

Andreas Kemnade andreas at kemnade.info
Mon Sep 24 12:54:46 CEST 2018


Hi Nikolaus,

On Mon, 24 Sep 2018 11:49:20 +0200
"H. Nikolaus Schaller" <hns at goldelico.com> wrote:

[...]
> 
> P12	gpio0/cd1
> N12	gpio1/cd2
> L4	gpio2
> P13	gpio15
> M4	gpio6/pwm0
> N14	gpio7/vibra/pwm1
> D8	gpio8/uart1.rxd
> L14	stp/gpio9
> L13	dir/gpio10
> M13	nxt/gpio11
> J13	data3/uart4.ctso/gpio12
> G14	data4/gpio14
> G13	data5/gpio3
> F14	data6/gpio4
> F13	data7/gpio5
> G11	gpio13/ledsync
> C3	gpio16/bt.pcm.vdr/dig.mic.clk0
> C5	gpio17/bt.pcm.vdx/dig.mic.clk1
> 
> Table 2.2 describes the signals and it appears that they are explicitly
> allowed to be floating if unused, because they have internal pull-downs
> active after reset.
> 
Well that is the theory. For the corresponding register, the default
after-reset values represent that. But in reality after boot everything
is disabled because twl4030-gpio sets them to 0 if not specified!

Regards,
Andreas
PS: twl4030-gpio should be compiled statically because:
        /* maybe setup IRQs */
        if (is_module()) {
                dev_err(&pdev->dev, "can't dispatch IRQs from modules\n");
                goto no_irqs;
        }

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