Re: iio dummy device doesn't appear in /sys/bus/iio/devices/

["Franziska Näpelt" <franziska.naepelt@googlemail.com>]

I just tried to use the kernel 4.4 iio dummy module and compiled it =
against kernel 4.9.
This works and creates an entry in sysfs.

To prevent dependencies I made an=20
#undef CONFIG_IIO_SIMPLE_DUMMY_BUFFER

> Am 05.06.2017 um 16:33 schrieb Franziska N=C3=A4pelt =
<franziska.naepelt@googlemail.com>:
>=20
> Hi,
>=20
> I=E2=80=99m just playing around with iio dummy drivers and couldn=E2=80=99=
t get it work with kernel 4.9 while everything was fine with=20
> kernel 4.4.
>=20
> Steps for kernel 4.4:
> * edit Kconfig to create IIO_SIMPLE_DUMMY module
> * build and install kernel
> * edit /etc/modules to load iio_dummy
> * after reboot there is an iio_dummy module loaded and the device =
appears in sysfs
>=20
> Steps for kernel 4.9:
> * edit Kconfig to create IIO_SW_DEVICE, IIO_SIMPLE_DUMMY, =
IIO_SIMPLE_DUMMY_BUFFER modules
> * build and install kernel
> * edit /etc/modules to load iio_dummy
> * after reboot there is an iio_dummy module loaded but doesn=E2=80=99t =
appear in sysfs
>=20
> Is there something wrong with the order, loading modules or do I miss =
some dependencies?
>=20
> Thanks,
> Franziska
>=20
> Here are some more detailed information, as first kernel 4.4, then =
4.9:
>=20
> Linux raspberrypi-3 4.4.50-v7+ #1 SMP Fri Jun 2 00:19:42 CEST 2017 =
armv7l GNU/Linux
> ---
> pi@raspberrypi-3:~/projects $ cat /etc/modules
> # /etc/modules: kernel modules to load at boot time.
> #
> # This file contains the names of kernel modules that should be loaded
> # at boot time, one per line. Lines beginning with "#" are ignored.
>=20
> iio_dummy
> ---
> pi@raspberrypi-3:~/projects/raspi-linux $ git diff =
drivers/staging/iio/Kconfig
> diff --git a/drivers/staging/iio/Kconfig b/drivers/staging/iio/Kconfig
> index 9d7f000..42d03a3 100644
> --- a/drivers/staging/iio/Kconfig
> +++ b/drivers/staging/iio/Kconfig
> @@ -23,6 +23,7 @@ config IIO_DUMMY_EVGEN
>=20
> config IIO_SIMPLE_DUMMY
>        tristate "An example driver with no hardware requirements"
> +          default y
>        help
>         Driver intended mainly as documentation for how to write
>         a driver. May also be useful for testing userspace code
> ---
> pi@raspberrypi-3:~/projects $ lsmod=20
> Module                  Size  Used by
> bnep                   10340  2=20
> hci_uart               17943  1=20
> btbcm                   5929  1 hci_uart
> bluetooth             326067  22 bnep,btbcm,hci_uart
> brcmfmac              186282  0=20
> brcmutil                5661  1 brcmfmac
> cfg80211              428833  1 brcmfmac
> rfkill                 16018  4 cfg80211,bluetooth
> snd_bcm2835            20447  0=20
> snd_pcm                75890  1 snd_bcm2835
> snd_timer              19288  1 snd_pcm
> bcm2835_gpiomem         2976  0=20
> snd                    51908  3 snd_bcm2835,snd_timer,snd_pcm
> bcm2835_wdt             3225  0=20
> uio_pdrv_genirq         3164  0=20
> uio                     8000  1 uio_pdrv_genirq
> iio_dummy               3072  0=20
> industrialio           33826  1 iio_dummy
> ipv6                  347563  32=20
> ---
> pi@raspberrypi-3:/sys/bus/iio/devices/iio:device0 $ ll
> insgesamt 0
> drwxr-xr-x  3 root root    0 Jun  4 13:42 .
> drwxr-xr-x 10 root root    0 Jun  4 13:42 ..
> -r--r--r--  1 root root 4,0K Jun  4 13:42 dev
> -rw-r--r--  1 root root 4,0K Jun  4 13:42 in_accel_x_calibbias
> -rw-r--r--  1 root root 4,0K Jun  4 13:42 in_accel_x_calibscale
> -rw-r--r--  1 root root 4,0K Jun  4 13:42 in_accel_x_raw
> -rw-r--r--  1 root root 4,0K Jun  4 13:42 in_activity_running_input
> -rw-r--r--  1 root root 4,0K Jun  4 13:42 in_activity_walking_input
> -rw-r--r--  1 root root 4,0K Jun  4 13:42 in_sampling_frequency
> -rw-r--r--  1 root root 4,0K Jun  4 13:42 in_steps_calibheight
> -rw-r--r--  1 root root 4,0K Jun  4 13:42 in_steps_en
> -rw-r--r--  1 root root 4,0K Jun  4 13:42 in_steps_input
> -rw-r--r--  1 root root 4,0K Jun  4 13:42 in_voltage0_offset
> -rw-r--r--  1 root root 4,0K Jun  4 13:42 in_voltage0_raw
> -rw-r--r--  1 root root 4,0K Jun  4 13:42 in_voltage0_scale
> -rw-r--r--  1 root root 4,0K Jun  4 13:42 in_voltage1-voltage2_raw
> -rw-r--r--  1 root root 4,0K Jun  4 13:42 in_voltage3-voltage4_raw
> -rw-r--r--  1 root root 4,0K Jun  4 13:42 in_voltage-voltage_scale
> -r--r--r--  1 root root 4,0K Jun  4 13:42 name
> -rw-r--r--  1 root root 4,0K Jun  4 13:42 out_voltage0_raw
> drwxr-xr-x  2 root root    0 Jun  4 13:42 power
> lrwxrwxrwx  1 root root    0 Jun  4 13:42 subsystem -> ../../bus/iio
> -rw-r--r--  1 root root 4,0K Jun  4 13:42 uevent
> =
--------------------------------------------------------------------------=
-----------------------------------------------
> Linux raspberrypi-3 4.9.30-v7+ #1 SMP Sun Jun 4 21:07:31 CEST 2017 =
armv7l GNU/Linux
> ---
> /etc/modules -> is the same
> ---=20
> pi@raspberrypi-3:~/projects/raspi-linux $ git diff drivers/iio/Kconfig=20=

> diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
> index 6743b18..e804f63 100644
> --- a/drivers/iio/Kconfig
> +++ b/drivers/iio/Kconfig
> @@ -49,6 +49,7 @@ config IIO_CONSUMERS_PER_TRIGGER
> config IIO_SW_DEVICE
>        tristate "Enable software IIO device support"
>        select IIO_CONFIGFS
> +       default y
>        help
>         Provides IIO core support for software devices. A software
>         device can be created via configfs or directly by a driver
> ---
> pi@raspberrypi-3:~/projects/raspi-linux $ git diff =
drivers/iio/dummy/Kconfig
> diff --git a/drivers/iio/dummy/Kconfig b/drivers/iio/dummy/Kconfig
> index aa5824d..1eb7991 100644
> --- a/drivers/iio/dummy/Kconfig
> +++ b/drivers/iio/dummy/Kconfig
> @@ -11,6 +11,7 @@ config IIO_DUMMY_EVGEN
> config IIO_SIMPLE_DUMMY
>        tristate "An example driver with no hardware requirements"
>        depends on IIO_SW_DEVICE
> +          default y
>        help
>         Driver intended mainly as documentation for how to write
>         a driver. May also be useful for testing userspace code
> @@ -29,6 +30,7 @@ config IIO_SIMPLE_DUMMY_BUFFER
>        select IIO_BUFFER
>        select IIO_TRIGGER
>        select IIO_KFIFO_BUF
> +       default y
>        help
>          Add buffered data capture to the simple dummy driver.
> ---
> pi@raspberrypi-3:~/projects/raspi-linux $ lsmod=20
> Module                  Size  Used by
> bnep                   12051  2=20
> hci_uart               20020  1=20
> btbcm                   7916  1 hci_uart
> bluetooth             365473  22 hci_uart,bnep,btbcm
> brcmfmac              222798  0=20
> brcmutil                9092  1 brcmfmac
> cfg80211              542989  1 brcmfmac
> rfkill                 20832  4 bluetooth,cfg80211
> snd_bcm2835            24427  0=20
> snd_pcm                98565  1 snd_bcm2835
> snd_timer              23904  1 snd_pcm
> bcm2835_gpiomem         3940  0=20
> snd                    70032  3 snd_timer,snd_bcm2835,snd_pcm
> uio_pdrv_genirq         3923  0=20
> fixed                   3285  0=20
> uio                    10268  1 uio_pdrv_genirq
> iio_dummy               4984  0=20
> industrialio_sw_device     3691  1 iio_dummy
> industrialio_configfs     1370  1 industrialio_sw_device
> kfifo_buf               3668  1 iio_dummy
> industrialio           62929  2 iio_dummy,kfifo_buf
> ipv6                  408530  32=20
> ---
> pi@raspberrypi-3:/sys/bus/iio/devices $ ll
> insgesamt 0
> drwxr-xr-x 2 root root 0 Jun  5 15:33 .
> drwxr-xr-x 4 root root 0 Jun  5 15:33 ..
>=20
>=20
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