Re: Reporting screen/laptop orientation data to userspace

From: Alberto Mardegan
Date: Mon Jun 06 2011 - 02:54:42 EST

On 06/03/2011 06:55 PM, Bastien Nocera wrote:
Do you also have a discrete accelerometer with that? Or you only ever
get notification through there?

There's a discrete accelerometer, but I suspect that it might be hard for its driver to get accepted into the mainline kernel, since it's directly playing with the EC I/O ports. It's this one:

The coarse data OTOH comes via a clean WMI interface.

If there is a discrete accelerometer, I'd drop the extra metadata, and
send an event through udev, and expect user-space to read from the
accelerometer instead.

You mean, send an event through udev when the WMI interface reports that the orientation has changed, and then expect the userspace to read the values from the accelerometer?
IMHO, reporting an event with no context data, it's inefficient and ugly (because it forces the userspace to perform additional acctions in order to get the data).

If there isn't a discrete accelerometer, create a fake one, with some
hardcoded data based on the actual orientation of the device.

This could be a solution in both cases (i.e., even if a discrete accelerometer is available). But it would be nice to have some flags on the input device which tell that this accelerometer is not as precise as one could desire. Is there such a thing?

The accelerometer (whether real or fake) should show 3 axis (X/Y/Z).

As soon as it's seen some testing, I'll be showing the work I did for
GNOME support for automatic rotation based on orientation.

Do you support choosing the accelerometer device to be used?

The device that I wanted to create is actually something much simpler than an accelerometer; it would just report screen orientation. I believe that some computer screens might have something similar, detecting the screen orientation based on the angle formed between the screen base (or wall mount) and the screen panel... I would assume that if such information exists, this Lenovo Ideapad screen orientation should be reported in a similar way.


-- <-- geek in un lingua international!
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