Message-ID: <20080924051417.GA29993@kroah.com>
Date:	Tue, 23 Sep 2008 22:14:17 -0700
From:	Greg KH <greg@...ah.com>
To:	Thomas Renninger <trenn@...e.de>
Cc:	Pavel Machek <pavel@...e.cz>, Tejun Heo <tj@...nel.org>,
	Shem Multinymous <multinymous@...il.com>,
	Elias Oltmanns <eo@...ensachen.de>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	IDE/ATA development list <linux-ide@...r.kernel.org>
Subject: Re: Laptop shock detection and harddisk protection

On Fri, Sep 19, 2008 at 11:03:58AM +0200, Thomas Renninger wrote:
> On Thursday 18 September 2008 13:18:45 Pavel Machek wrote:
> > On Wed 2008-09-17 11:04:05, Greg KH wrote:
> > > On Sun, Aug 17, 2008 at 09:45:21PM +0200, Pavel Machek wrote:
> > > > On Fri 2008-09-12 09:59:47, Greg KH wrote:
> > > > > On Fri, Sep 12, 2008 at 01:35:54AM +0200, Tejun Heo wrote:
> > > > > > Shem Multinymous wrote:
> > > > > > >> That reduction comes because input device supports poll and
> > > > > > >> sysfs_notify_event() does about the same thing.  The uesrland
> > > > > > >> daemon can just poll on a node and read data nodes when poll
> > > > > > >> event on the node triggeres.
> > > > > > >
> > > > > > > Agreed.
> > > > > > > There's another issue with the current sysfs interface, though:
> > > > > > > hdapsd needs to read (x,y,timestamp) tuples, whereas sysfs
> > > > > > > provides just x and y in separate attributes which cannot be read
> > > > > > > atomically together. We can add a sysfs file with "x y timestamp"
> > > > > > > readouts, though this is unusual for sysfs (and certainly
> > > > > > > incompatible with hwmon).
> > > > > >
> > > > > > Yes, right.  Forgot about the atomicity part altogether.  Thanks
> > > > > > for bringing it up.
> > > > > >
> > > > > > >> Unloading heads will be simple.  Just echoing timeout in ms to
> > > > > > >> sysfs nodes, so I don't think it's a good idea to push out
> > > > > > >> actual unloading to another process especially as fork doesn't
> > > > > > >> inherit mlockall.
> > > > > > >
> > > > > > > I had in mind another daemon listening for "unload now" events,
> > > > > > > so no forking needed.
> > > > > > > This second daemon might make sense if we push the logic of
> > > > > > > deciding *which* disks to unload into userspace, since this logic
> > > > > > > is the same for the ThinkPad style and the HP style.
> > > > > >
> > > > > > Hmmm... I can't (yet) see the benefit of having two separate
> > > > > > userland daemons.
> > > > > >
> > > > > > >> On a related note, is there any plan to merge tp_smapi to
> > > > > > >> mainline? It seems you put a lot of work into it and I don't
> > > > > > >> really see why it should stay out of tree.
> > > > > > >
> > > > > > > The only issue I'm aware of is finding a reasonably-named
> > > > > > > maintainer. On the technical side, the reviews on my lkml
> > > > > > > submission of thinkpad_ec+hdaps seemed good and all technical
> > > > > > > comments are since addressed. The code has been stable,
> > > > > > > well-tested and packaged by major distros for years.
> > > > > >
> > > > > > Cool, can you please post the patch to the lkml and cc Greg
> > > > > > Kroah-Hartman <gregkh@...e.de>, Andrew Morton
> > > > > > <akpm@...ux-foundation.org> and me?
> > > > >
> > > > > Sorry, but no, I can't accept this code as it is coming from a "known
> > > > > anonymous" person containing information that it is not known where
> > > > > it came from.
> > > >
> > > > So... what are you worried about?
> > >
> > > Code created by access to specs that were not allowed to be published in
> > > GPL form by someone who wants to remain anonymous.
> >
> > That anonymous person may have problems if they signed NDA.
> >
> > I don't think they did, they even list the sources:
> >
> >  *  The embedded controller on ThinkPad laptops has a non-standard
> > interface, *  where LPC channel 3 of the H8S EC chip is hooked up to IO
> > ports *  0x1600-0x161F and implements (a special case of) the H8S LPC
> > protocol. *  The EC LPC interface provides various system management
> > services (currently *  known: battery information and accelerometer
> > readouts). This driver *  provides access and mutual exclusion for the EC
> > interface.
> > *
> >  *  The LPC protocol and terminology is documented here:
> >  *  "H8S/2104B Group Hardware Manual",
> >  * 
> > http://documentation.renesas.com/eng/products/mpumcu/rej09b0300_2140bhm.pdf
> >
> > H8S chip seems to be documented.
> Hmm, the EC is not directly used, but ACPI functions of the HP device are 
> used.
> For the HP ACPI device: the ACPI functions can *very easily* be re-engineered
> (which is common for all laptop_acpi.ko drivers):
> ALRD -> is used by the driver to read out registers of the accelerometer
> ALWR -> is used by the driver to write a registers of the accelerometer
> BTW: HP likes to have support for their device.
> 
> The acceleromter chip itself is docuemented in detail here:
> http://www.st.com/stonline/products/literature/ds/12094/lis3lv02dl.pdf
> 
> I also do not see any concerns.
> Greg: Can you please add this one or explain in more detail what else you like 
> to see to get this integerated.

If you, or anyone else, writes a new driver from the published
documents, that driver can be accepted.  It can not be based on the
existing code written by Shem in any form.

We can not accept this driver for reasons I've detailed numerous times
in the past.  That fact isn't going to change, sorry.

thanks,

greg k-h
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