linux-kernel - Re: screen rotation flipped in 4.8-rc

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Date:   Fri, 02 Sep 2016 15:48:07 -0700
From:   Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
To:     "linux@...encehorizons.net" <linux@...encehorizons.net>,
        "jic23@...nel.org" <jic23@...nel.org>,
        "hadess@...ess.net" <hadess@...ess.net>,
        Grant Likely <glikely@...retlab.ca>, jikos@...nel.org
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>
Subject: Re: screen rotation flipped in 4.8-rc

On Tue, 2016-08-30 at 22:42 +0000, Pandruvada, Srinivas wrote:
> Hi All,
> 
> I observed that using iio-sensor-proxy.service, the auto screen
> rotation flipped on my laptop (Normal -> vertical, vertical->normal)
> using kernel v4.8.
> 
> Anyone else has seen this?
> 
> I did a bisect and found a commit, which I am not sure how can it
> impact.
> 
> 
> commit 703b5faf22fbddf984a361e6555f3a03fdba63d9
> Author: George Spelvin <linux@...encehorizons.net>
> Date:   Fri Jun 10 00:22:12 2016 -0400
> 
[...]

It turns out to be some assumption user space program is making about
the traversing directory using glib call g_dir_read_name(). 

With the commit 703b5faf22fbddf984a361e6555f3a03fdba63d9 (fs/dcache.c:
Save one 32-bit multiply in dcache lookup)
 in kernel 4.8-rc, somehow the order is changed (so the in_accel_y was
appearing before in_accel_x )

I modified user space program to use correct iio scan element index to
determine byte offset instead depending on the glib_dir_read_name,
which doesn't guarantee any order.

I sent a pull request to author of iio-sensor-proxy to review.

Hadess,
	Please look.

https://github.com/hadess/iio-sensor-proxy/pull/99/commits/de80c50b2678
2ba6e899ee5a95b31b28790c940d


Thanks,
Srinivas