GPIO sysfs 'default' values
Hi Grant, Linus.
I was testing our new gpio/pinctrl driver today and noticed something a little weird.
I exported gpio0 via sysfs and echoed the direction value - it was 'in'. This pin is used to control an LCD panel, and is actually in 'out' mode. If I write 'in' to direction, it changes mode to 'in' and the panel turns off. Setting it back to 'out' and value=0, and the panel turns on again.
I noticed that I had no gpiochip->get_direction, so I added it, but the result was the same.
Any idea what I've missed?
Regards
Tony Prisk
Quoted 11 lines · Tony Prisk
Hi Grant, Linus.
I was testing our new gpio/pinctrl driver today and noticed something a little weird.
I exported gpio0 via sysfs and echoed the direction value - it was 'in'. This pin is used to control an LCD panel, and is actually in 'out' mode. If I write 'in' to direction, it changes mode to 'in' and the panel turns off. Setting it back to 'out' and value=0, and the panel turns on again.
Quoted 7 lines
I noticed that I had no
gpiochip->get_direction, so I added it, but the result was the same.Any idea what I've missed?
Regards
Tony Prisk
Sorted it out.
->get_direction was all that was needed.
Apologies,
Tony P
Hi,
Quoted 11 lines · Tony Prisk
Hi Grant, Linus.
I was testing our new gpio/pinctrl driver today and noticed something a little weird.
I exported gpio0 via sysfs and echoed the direction value - it was 'in'. This pin is used to control an LCD panel, and is actually in 'out' mode. If I write 'in' to direction, it changes mode to 'in' and the panel turns off. Setting it back to 'out' and value=0, and the panel turns on again.
Quoted 5 lines
I noticed that I had no
gpiochip->get_direction, so I added it, but the result was the same.Any idea what I've missed?
You missed to report on what platform this happens.
The platform specific GPIO driver obviously does not initialize the shadow variables for the hardware registers correctly.
Lothar Wa?mann
Signature · 9 lines
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