linux-kernel - Re: [PATCH] lis3lv02d: add axes knowledge of HP Pavilion dv5 models

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Date:	Tue, 10 Feb 2009 22:28:58 +0100
From:	Giuseppe Bilotta <giuseppe.bilotta@...il.com>
To:	Éric Piel <E.A.B.Piel@...elft.nl>
Cc:	Éric Piel <eric.piel@...mplin-utc.net>,
	Palatis Tseng <palatis@...il.com>,
	Pavel Machek <pavel@...e.cz>,
	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] lis3lv02d: add axes knowledge of HP Pavilion dv5 models

On Tue, Feb 10, 2009 at 1:42 PM, Éric Piel <E.A.B.Piel@...elft.nl> wrote:
> Can you try something like this in lis3lv02d_poweron():
>        adev.read(handle, CTRL_REG2, &val);
>        val |= CTRL2_BDU | CTRL2_IEN;
> +       val &= ~CTRL2_BLE;
>        adev.write(handle, CTRL_REG2, val);

Ok, this is getting crazier and crazier. Apparently, setting the
CTRL2_BLE bit this way makes no difference, and so does setting it
with val |= (i.e. enabling it): in both cases, if I debug
lis3lv02d_read_16 I always get 0 in the lower byte and something in
the upper byte.

By forcefully swapping lo and hi I actually get very little
fluctuations in the Y and Z axes (so small that jstest doesn't detect
them), but I still get huge (4k) fluctuations in the X axis:
apparently, this axis has very small SIGNED fluctuations around the 0,
which translate to fluctuations between 255 and 1

Now, the lo/hi thing might be solved some other way (e.g. by checking
the BLE bit and relying on its setting instead of trying to force it,
and then swapping hi and lo as needed). But how do we solve the
SIGNEDNESS of lo ?


-- 
Giuseppe "Oblomov" Bilotta
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