linux-kernel - Re: [PATCH] ACPI / Battery: Return -ENODATA for unknown values in get

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Date:	Sun, 17 Oct 2010 15:50:25 +0100
From:	Sitsofe Wheeler <sitsofe@...oo.com>
To:	Henrique de Moraes Holschuh <hmh@....eng.br>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	Len Brown <lenb@...nel.org>, Zhang Rui <rui.zhang@...el.com>,
	David Zeuthen <davidz@...hat.com>,
	Richard Hughes <richard@...hsie.com>,
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ACPI / Battery: Return -ENODATA for unknown values in
	get_property()

On Sun, Oct 17, 2010 at 11:10:16AM -0200, Henrique de Moraes Holschuh wrote:
> On Sun, 17 Oct 2010, Sitsofe Wheeler wrote:
> > 
> > Using ENODATA and ENXIO appears to solve the problem (upower reports a
> > rate of 0.0). However when plugging the battery in after previously only
> > being on AC power none of the /sys/class/power_supply/BAT0/uevent:*
> > files are created so upower never realises a battery has been plugged
> 
> You might have broken firmware that does not issue a notify when a battery
> is plugged.  But it has been a long time, I don't recall if the battery
> driver handles hotplugging without the help of the dock/bay driver (it
> should, AFAIK).

Battery hotplug works fine without these patches. I should have said -
the uevent devices are there with a vanilla kernel no matter how many
times the battery is plugged in or unplugged (that's how I knew they
were missing with the patches added :) I am guessing some part of the
kernel/udev cannot handle being told ENODATA or ENXIO and bails out
before those nodes would be made.

> > in. A further issue with ENXIO is is the following repeatedly appears in
> > dmesg:
> > power_supply BAT0: driver failed to report `current_now' property
> 
> And it keeps silent if it gets ENODATA?

Yes.

-- 
Sitsofe | http://sucs.org/~sits/
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