linux-kernel - Re: iio/hid-sensor-accel-3d: no output from /dev/iio:device*?

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Message-ID: <1450400312.5427.15.camel@intel.com>
Date:	Fri, 18 Dec 2015 01:00:21 +0000
From:	"Pandruvada, Srinivas" <srinivas.pandruvada@...el.com>
To:	"jikos@...nel.org" <jikos@...nel.org>,
	"nish.aravamudan@...il.com" <nish.aravamudan@...il.com>
CC:	"lars@...afoo.de" <lars@...afoo.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"knaack.h@....de" <knaack.h@....de>,
	"jic23@...nel.org" <jic23@...nel.org>,
	"cmo@...exis.com" <cmo@...exis.com>,
	"linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
	"pmeerw@...erw.net" <pmeerw@...erw.net>,
	"linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
	"Shevchenko, Andriy" <andriy.shevchenko@...el.com>
Subject: Re: iio/hid-sensor-accel-3d: no output from /dev/iio:device*?

Hi Andy,

As per Nish these patches are impacting sensors on Yoga.
https://lkml.org/lkml/2015/11/30/441

Can you help?

Thanks,
Srinivas

On Thu, 2015-12-17 at 16:51 -0800, Srinivas Pandruvada wrote:
> On Thu, 2015-12-17 at 15:38 -0800, Nish Aravamudan wrote:
> > [Starting a new thread from https://lkml.org/lkml/2015/12/15/663,
> > as
> > now my laptop is displaying values in the sysfs *raw* files.]
> > 
> > So I'm trying to understand exactly how the hid-sensor-accel-3d
> > driver works.
> > 
> > If I turn up debugging, when I `cat
> > /sys/bus/iio/devices/device*/*raw*`, I see "iio iio:device3:
> > accel_3d_proc_event" and I think that means that
> > hid_sensor_push_data() is getting called.
> > 
> > But read()'s on /dev/iio:device3 never produces anything, which is
> > what iio-sensor-proxy uses to translate events to dbus.
> > 
> > Is it expected that the dev-node is "silent"? Just trying to
> > understand if an extension to the driver to support a chardev based
> > output is appropriate, or if iio-sensor-proxy needs to be changed
> > to
> > handle this device.
> 
> You are saying there is some regression. This used to work and now it
> doesn't work. Is raw values are displayed correctly, when you do
> "cat"?
> If cat of raw values is working then power on of sensors is working.
> 
> Turn on HID debug prints. If it is regression we can do git bisect.
> Any ACPI or PM changes can break this. Usually there will be GPIOs
> which will be involved in power on, where ACPI comes into play. This
> will be done by i2c-hid. There are some prints in i2c-hid which can
> be
> enabled also.
> 
> Thanks,
> Srinivas
> 
> >