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Opened 7 years ago

Last modified 4 years ago

#9514 new defect

Device /dev/gpio not created

Reported by: Nicolas Le Falher <n.lefalher@…> Owned by: developers
Priority: normal Milestone: Barrier Breaker 14.07
Component: packages Version: Trunk
Keywords: gpio_dev Cc: 27114

Description

On platform RDC/Bifferboard device /dev/gpio is not created.

root@OpenWrt:/# uname -a
Linux OpenWrt 2.6.32.33 #1 Mon Jun 6 19:45:15 CEST 2011 i486 GNU/Linux
root@OpenWrt:/# dmesg | grep gpio
rdc321x-gpio rdc321x-gpio: registering 58 GPIOs 
root@OpenWrt:/# lsmod | grep gpio_dev
gpio_dev                1012  0
root@OpenWrt:/# gpioctl set 1
Error whilst opening /dev/gpio
root@OpenWrt:/# ls /dev/ | grep gpio
root@OpenWrt:/#

Regards.

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Change History (5)

comment:1 Changed 7 years ago by florian

ok, I see why this does not work, the platform_device is not created, what is wrong with using sysfs gpio like I proposed first? There is nothing it cannot do that gpioctl does, besides, gpio_dev is a non standard interface to driving gpios.

comment:2 Changed 7 years ago by Nicolas Le Falher <n.lefalher@…>

It's just for know why it not work, and no rewrite some code to sysfs.
I read on a ticket gpio dev was three time faster than gpio sysfs.

But if now gpio_dev is deprecated, and the new standard is sysfs for manage gpio, I think I must switch on it.

comment:3 follow-up: Changed 7 years ago by florian

In any case, if you need to quickly toggle some GPIOs, you will have to write a kernel module to do that, otherwise, the cost of the context switch and such will dramatically slown down the gpio toggling. gpioctl/kmod-gpio-dev are fast because the command is received from user-space and the toggling is done in kernel.

comment:4 in reply to: ↑ 3 Changed 6 years ago by anonymous

Replying to florian:

In any case, if you need to quickly toggle some GPIOs, you will have to write a kernel module to do that, otherwise, the cost of the context switch and such will dramatically slown down the gpio toggling. gpioctl/kmod-gpio-dev are fast because the command is received from user-space and the toggling is done in kernel.

Yes, I agree with you, sysfs would be slower than the gpioctl

comment:5 Changed 4 years ago by jow

  • Milestone changed from Attitude Adjustment 12.09 to Barrier Breaker 14.07

Milestone Attitude Adjustment 12.09 deleted

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