Unfortunately, that's the command that gives me the error message.  Someone 
else has control of those gpio's and I can unexport them, even as root.

--Mark

On Wednesday, November 29, 2017 at 9:34:35 AM UTC-5, William Hermans wrote:
>
>
>
> On Wed, Nov 29, 2017 at 7:27 AM, Mark A. Yoder <[email protected] 
> <javascript:>> wrote:
>
>> That fixed it.  Thanks...
>>
>> Now I see all sorts of gpios are already exported.
>> export   gpio114  gpio13  gpio22  gpio30  gpio46  gpio50  gpio66  
>> gpiochip0
>> gpio110  gpio115  gpio14  gpio23  gpio31  gpio47  gpio51  gpio67  
>> gpiochip32
>> gpio111  gpio116  gpio15  gpio26  gpio4   gpio48  gpio60  gpio68  
>> gpiochip64
>> gpio112  gpio117  gpio2   gpio27  gpio44  gpio49  gpio61  gpio69  
>> gpiochip96
>> gpio113  gpio12   gpio20  gpio3   gpio45  gpio5   gpio65  gpio7   unexport
>>
>> I want to unexport a couple (14, 113 and 115) so the *fbtft_device* 
>> kernel driver and access them.  But I get and error
>> echo: write error: Invalid argument
>>
>> How do I unexport them?
>>
>>>
>>>  
> as root:
>
> echo xxx > /sys/class/gpio/unexport
>
> Where xxx == the gpioxxx value you wish to reclaim.
>
> So in the example case of gpio112 . . .
>
> echo 112 > /sys/class/gpio/unexport
>
>

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