linux-kernel - Re: [Hdaps-devel] [PATCH 2.6.23-rc2] hwmon: HP Mobile Data Protection System 3D ACPI driver (resend)

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Date:	Wed, 29 Aug 2007 20:31:04 -0400
From:	"Shem Multinymous" <multinymous@...il.com>
To:	"Henrique de Moraes Holschuh" <hmh@....eng.br>
Cc:	"Yan Burman" <burman.yan@...il.com>,
	hdaps-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
	"Pavel Machek" <pavel@....cz>
Subject: Re: [Hdaps-devel] [PATCH 2.6.23-rc2] hwmon: HP Mobile Data Protection System 3D ACPI driver (resend)

On 8/29/07, Henrique de Moraes Holschuh <hmh@....eng.br> wrote:
> On Wed, 29 Aug 2007, Yan Burman wrote:

> HDAPS with input device support is quite new.  hdapsd was patched to talk to
> it, too.  I suppose we should port the input device support to the driver
> in-tree just so that we get it in tree as well.  Sounds like an useful
> reason to bother with in-tree hdaps.  Not that it will save much power with
> the in-tree driver, but at least it will be widely available from there.

In case they'll be of help for such porting, the relevant hdaps
patches from my tp_smapi patch series are attached.


> > I agree that the sys interface is probably not the best choice, but the
> > accelerometer data should provide not only position, but also generate
> > an event when it detects
> > that it's falling. From what I understood hdaps does not have that info,
>
> You can generate events on input devices, but I am not sure that's the best
> way to go about it for this.  Things that block on read until an interrupt
> happens might work better.

You can do the latter via another (4th) input device.


> I'd suggest an accelerometer sysfs interface, that we implement in hdaps
> (in and out-of-tree), ams and hpmdp.  One input device for joystick
> emulation (optional), one input device with accelerometer data in mg or ug,

Is any of the accelerometer drivers currently capable of computing the
physical acceleration? Also, is there an issue of linear vs. angular
acceleration?


> and an optional one with the raw accelerometer data.

Before or after axis inversion/swapping? The tp_smapi hdaps driver
(losslessly) inverts the raw data too, to avoid duplication of
model-specific orientation logic.


> unless someone wants to implement their own free-fall algorithms instead of
> using whatever is in the firmware).

The term "free-fall" is dangerously misleading, for the reasons
explained in the IBM APS whitepaper.

  Shem

View attachment "0001-hdaps-Add-ID-fields-to-the-hdaps-joystick-emulation.patch" of type "text/x-patch" (2268 bytes)

View attachment "0002-hdaps-Add-a-2nd-input-device-for-raw-accelerometer.patch" of type "text/x-patch" (4635 bytes)