[Letux-kernel] GPIO 174

[H. Nikolaus Schaller]

Hi,

> Am 05.02.2018 um 11:03 schrieb Andreas Kemnade <andreas at kemnade.info>:
> 
> Hi,
> 
> GPIO 174 seems strange:
> 
> # devmem2 0x480021CC w
> /dev/mem opened.
> Memory mapped at address 0xb6f1b000.
> Value at address 0x480021CC (0xb6f1b1cc): 0x11C011C
> 
> So it is configured as *input*? uboot configures it as such.
> Is that correct? Or am I misreading something.

That pad control is special with omap and not completely intuitive.
The config as "input" doesnot mean that it is no output...
It just says that the pad always sends the current state to the gpio bank
and you can read ack the real pad state.
If it is used as output is not configured on the pinmux but by the gpio bank
(or whatever controller is used).

	• INPUTENABLE (1 bit) drives an input enable signal to the I/O CTRL.
		• –  INPUTENABLE = 0: Input Disable. Pin is configured in output only mode.
		• –  INPUTENABLE = 1: Input Enable. Pin is configured in bidirectional mode.

> 
> # devmem2 0x4905803C w
> /dev/mem opened.
> Memory mapped at address 0xb6f25000.
> Value at address 0x4905803C (0xb6f2503c): 0x0
> 
> It seems to react properly on ehci-omap actions
> 
> root at gta04:~# devmem2 0x4905803C w
> /dev/mem opened.
> Memory mapped at address 0xb6f9d000.
> Value at address 0x4905803C (0xb6f9d03c): 0x4000
> root at gta04:~# rmmod ehci-omap
> root at gta04:~# devmem2 0x4905803C w
> /dev/mem opened.
> Memory mapped at address 0xb6f25000.
> Value at address 0x4905803C (0xb6f2503c): 0x0
> 
> Regards,
> Andreas
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