linux-kernel - Re: [PATCH] Explicitly disable BT radio using rfkill interface on suspend

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Date:	Tue, 19 May 2009 06:03:27 +0100
From:	Matthew Garrett <mjg59@...f.ucam.org>
To:	Mario Limonciello <mario_limonciello@...l.com>
Cc:	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Explicitly disable BT radio using rfkill interface on
	suspend

On Mon, May 18, 2009 at 04:36:40PM -0500, Mario Limonciello wrote:

> Dell BT adapters will startup in a HID mode.  In HID mode two logical
> USB devices are exposed, a mouse and a keyboard.  If properly set, the
> BT radio will work with pre-paired keyboards or mice in this mode.  This
> is useful for things like BIOS control via a BT keyboard.  A command is
> sent to one of the descriptors of the mouse to cause the device to
> transition to HCI mode.  When transitioned to HCI mode, a radio device
> is exposed allowing it to pair and operate with any BT device.
> 
> Here's what the utility looks like that ships with bluez:
> http://git.kernel.org/?p=bluetooth/bluez.git;a=blob;f=tools/hid2hci.c;h=11d707fd76e940b884c9078907ab1504cd7350d4;hb=HEAD
> Look at the switch_dell method to see how it works.
> 
> Currently, this is implemented via a set of udev rules shipped with
> bluez that match the Dell device and transition it to HCI mode.
> Here's the udev rule that matches:
> ACTION=="add", ENV{ID_VENDOR}=="413c", ENV{ID_CLASS}=="mouse", ATTRS{bmAttributes}=="e0", KERNEL=="mouse*", RUN+="/usr/sbin/hid2hci --method dell -v $env{ID_VENDOR} -p $env{ID_MODEL} --mode hci"
> 
> When coming out of S3 if the killswitch isn't activated, the logical USB
> mouse isn't coldplugged again preventing the udev rule from being
> matched upon.  You can manually run hid2hci and the device will switch
> modes.

Ok. I don't think the right way to implement this is forcing dell-laptop 
to simulate an unplug. The HCI driver should be responsible for saving 
and restoring state of the device in its suspend/resume method.

-- 
Matthew Garrett | mjg59@...f.ucam.org
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