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

[Jonathan Cameron <jic23@jic23.retrosnub.co.uk>]

Hi Francis

Change was made from just creating one dummy instance, to providing a configfs entry to 
create them on demand.

https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git/commit/drivers/iio/dummy/iio_simple_dummy.c?h=testing&id=3d85fb6f81046b51e4428e14fb9643ea75648630

The commit log talks about how to create them.
You will need configfs mounted though if it is not already.

mount -t configfs none /config

Putting back old code would have gone back to old creation method.

Jonathan




On 5 June 2017 18:41:39 BST, "Franziska Näpelt" <franziska.naepelt@googlemail.com> wrote:
>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 
>#undef CONFIG_IIO_SIMPLE_DUMMY_BUFFER
>
>> Am 05.06.2017 um 16:33 schrieb Franziska Näpelt
><franziska.naepelt@googlemail.com>:
>> 
>> Hi,
>> 
>> I’m just playing around with iio dummy drivers and couldn’t get it
>work with kernel 4.9 while everything was fine with 
>> kernel 4.4.
>> 
>> 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
>> 
>> 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’t appear
>in sysfs
>> 
>> Is there something wrong with the order, loading modules or do I miss
>some dependencies?
>> 
>> Thanks,
>> Franziska
>> 
>> Here are some more detailed information, as first kernel 4.4, then
>4.9:
>> 
>> 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.
>> 
>> 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
>> 
>> 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 
>> Module                  Size  Used by
>> bnep                   10340  2 
>> hci_uart               17943  1 
>> btbcm                   5929  1 hci_uart
>> bluetooth             326067  22 bnep,btbcm,hci_uart
>> brcmfmac              186282  0 
>> brcmutil                5661  1 brcmfmac
>> cfg80211              428833  1 brcmfmac
>> rfkill                 16018  4 cfg80211,bluetooth
>> snd_bcm2835            20447  0 
>> snd_pcm                75890  1 snd_bcm2835
>> snd_timer              19288  1 snd_pcm
>> bcm2835_gpiomem         2976  0 
>> snd                    51908  3 snd_bcm2835,snd_timer,snd_pcm
>> bcm2835_wdt             3225  0 
>> uio_pdrv_genirq         3164  0 
>> uio                     8000  1 uio_pdrv_genirq
>> iio_dummy               3072  0 
>> industrialio           33826  1 iio_dummy
>> ipv6                  347563  32 
>> ---
>> 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
>> --- 
>> pi@raspberrypi-3:~/projects/raspi-linux $ git diff
>drivers/iio/Kconfig 
>> 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 
>> Module                  Size  Used by
>> bnep                   12051  2 
>> hci_uart               20020  1 
>> btbcm                   7916  1 hci_uart
>> bluetooth             365473  22 hci_uart,bnep,btbcm
>> brcmfmac              222798  0 
>> brcmutil                9092  1 brcmfmac
>> cfg80211              542989  1 brcmfmac
>> rfkill                 20832  4 bluetooth,cfg80211
>> snd_bcm2835            24427  0 
>> snd_pcm                98565  1 snd_bcm2835
>> snd_timer              23904  1 snd_pcm
>> bcm2835_gpiomem         3940  0 
>> snd                    70032  3 snd_timer,snd_bcm2835,snd_pcm
>> uio_pdrv_genirq         3923  0 
>> fixed                   3285  0 
>> uio                    10268  1 uio_pdrv_genirq
>> iio_dummy               4984  0 
>> 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 
>> ---
>> 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 ..
>> 
>> 
>> 
>> 
>
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