Hello Elad, In order to confirm this is a bug against the newest kernel it is best to have steps to reproduce the issue. I understand that iio-sensor-proxy fails to read the iio accelerometer. This could be an issue with the kernel or with the application's uses of the sysfs/device driver interface. Documentation on the iio subsystem sysfs interface can be found here: https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-bus-iio The basic idea is store an iio device driver interface in the folder /sys/bus/iio/devices Each device will have a folder iio:deviceX. In each iio device directory there should be a "name" file, and a "buffer" and "scanning_elements" folder. The "name" file is simply the device driver name, for the accelerometer it should be called "accel-3d". To Test this driver you must enable the scanning elements, in this cases the axises (x, y, z), and then enable the buffer. To enable the scanning x axis element just write "1" into the file "in_accel_x". Example: # echo -n 1 > /sys/.../iio:deviceX/scan_elements/in_accel_x_en # echo -n 1 > /sys/.../iio:deviceX/scan_elements/in_accel_y_en # echo -n 1 > /sys/.../iio:deviceX/scan_elements/in_accel_z_en Now that we have setup the data we wish to read, we can enable the internal iio scan buffer. This is done in a similar way, the iio sysfs folder "buffer" contains a file "enable" that we set to 1. Example: # echo -n 1 > /sys/bus/iio/devices/iio:deviceX/buffer/enable To read data from the buffer you must read the character device found at /dev/iio:deviceX, where X matches the same number for the syfs folder we were modifying. Example: #cat /dev/iio:deviceX The above is how the iio-sensor-proxy reads data. You should be aware that the charecter device (/dev/iio:deviceX) can only be read once, if some other app is already reading from this device it will return busy/resource unavailable. Therefore you must ensure nothing is reading from it already and that iio-sensor-proxy is disabled. This can be checked with command lsof. Example: # lsof | grep /dev/iio:deviceX >From the steps above hopefully you can reproduce the same error, of not being able to read from the char device on the newest kernel. If the above commands all work correctly and data is returned it is mostly likely a bug in iio-sensor-proxy or some other part of the kernel that that application uses. To debug this iio device problem further it helps to enable extra debugging information. Dynamic debugging allows the user to enable switches to give extra information when the kernel prints debugging information. Documentation for dynamic debugging can be found here: https://www.kernel.org/doc/Documentation/dynamic-debug-howto.txt You can turn on dynamic debugging after boot by writing to the dynamic debugging file found in the debugfs interface. It is easier for me to enable the feature at boot. This is done by adding a line to the modprobe config. This can be found in /etc/modprobe.d/iio.conf. In this file add a line that enables dynamic debugging for modules hid-sensor-accel-3d and hid-sensor-hub. The lines should be: options hid-sensor-accel-3d dyndbg=+pflt options hid-sensor-hub dyndbg=+pflt This features needs debugging support in the kernel so it is best to build the newest kernel 3.17-rc1 with debugging to get the most output in dmesg. To access the devices usb hid report you can print this from the debugfs interface. You sent me "Bus 002 Device 003: ID 0483:91d1 STMicroelectronics" from lsusb output. This means the usb device is found on bus 2 and is device 3. The usb hid id is 0483:91d1. The first half is the vendor id (STMicroelectronics) and the second half is the product id. The report information for this device will be found at: /sys/kernel/debug/hid/0483:91d1.X/rdesc Where X is the interface number if your device has more than one. I hope this information helps you and is all correct. If you need any more help please let me know, Reyad Attiyat On Tue, Aug 19, 2014 at 11:51 AM, Elad Alfassa <elad@xxxxxxxxxxxxxxxxx> wrote: > Hey. > > can you instruct me on: > > 1) how to turn on this dynamic debugging thing? > 2) How do I know which directory in /sys/kernel/debug/hid/ is the one > for the accelerometer? > > The USB device ID is Bus 002 Device 003: ID 0483:91d1 STMicroelectronics > > The weird thing is that after suspend & resume, iio-sensor-proxy can > suddenly read the values from the sensor, but it still doesn't rotate > the screen. > > > > On Tue, Aug 12, 2014 at 7:42 PM, Reyad Attiyat <reyad.attiyat@xxxxxxxxx> wrote: >> Hello Elad Alfassa, >> >> I'm not too sure exactly what has caused such a regression but I will >> try and help. There was very little added to the accelerometer driver >> in between those releases only, some slight power modifications and >> raw read support. >> >> Have you tried using the sysfs interface for the IIO accelerometer. >> Should be located in /sys/bus/iio/devices/iio:devicex/ >> In that directory, on the newest kernel, there should be a >> in_accel_x_raw file, can you read new data from this? >> >> Can you provide more detail about the error. Turn on dynamic debugging >> for hid-sensor-hub and hid-sensor-accel-3d modules. Then try enabling >> the scan elements and the buffer with the sysfs interface and post the >> full dmesg output. Also print the HID report description found on >> debugfs usually somewhere like >> (/sys/kernel/debug/hid/xxxx:xxxx:/rdesc) Maybe with this extra >> information the problem will be more clear. >> >> For a possible fix you can try adding the devices USB HID ID's, for >> the sensor hub, to the hid-sensor-hub driver hid_device_id struct. >> This will allow adding a quirk for your device and should setup the >> power state and enable the sensor hub correctly. >> >> Good luck, >> Reyad Attiyat >> >> On Mon, Aug 11, 2014 at 8:51 AM, Elad Alfassa <elad@xxxxxxxxxxxxxxxxx> wrote: >>> On Mon, Aug 11, 2014 at 3:16 PM, Elad Alfassa <elad@xxxxxxxxxxxxxxxxx> wrote: >>>> Hi. >>>> >>>> I have a Thinkpad Twist, this is a Windows 8 certified machine from >>>> around 2012, and it has an accelerometer. >>>> Running kernel 3.16.0-1.fc22.x86_64, I'm getting "Resource Temporarily >>>> Unavailable" when trying to read from the accelerometer. >>>> >>>> Tiny bit more details: >>>> https://github.com/hadess/iio-sensor-proxy/issues/1 >>>> https://sysdev.microsoft.com/en-us/hardware/LPL/ProductDetails.aspx?ProductID=98463&OrganizationID=4733 >>>> >>>> Is this a known issue? Can I help debug this in any way? >>>> >>>> >>>> Thanks. >>>> >>>> -- >>>> -Elad Alfassa. >>> >>> Hi. >>> Turns out this is a regression - it works well with kernel >>> 3.15.8-200.fc20.x86_64 >>> I tried reporting this in the kernel bugzilla, but I couldn't find the >>> right component for the bug, so I filed it in RHBZ for now. >>> https://bugzilla.redhat.com/show_bug.cgi?id=1128760 >>> >>> >>> -- >>> -Elad Alfassa. >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-iio" in >>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>> More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > -- > -Elad Alfassa. -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
