2009-08-04 12:30:40

by Andrey Borzenkov

[permalink] [raw]
Subject: Multiple rfkill knobs for the same hardware interface

This is mostly the same situation as ACPI vs. platform backlight
control. Here on Dell XPS M1330:

{pts/1}% rfkill list
0: dell-wifi: Wireless LAN
Soft blocked: no
Hard blocked: no
1: dell-bluetooth: Bluetooth
Soft blocked: no
Hard blocked: no
2: phy0: Wireless LAN
Soft blocked: no
Hard blocked: no
4: hci0: Bluetooth
Soft blocked: no
Hard blocked: no

Arguably, either one in the pair is redundant. Moreover, hard disabling
wireless (using slider on notebook side):

{pts/1}% rfkill list
0: dell-wifi: Wireless LAN
Soft blocked: no
Hard blocked: no
1: dell-bluetooth: Bluetooth
Soft blocked: no
Hard blocked: no
2: phy0: Wireless LAN
Soft blocked: no
Hard blocked: yes

So dell-laptop actually lies claiming that both radios are enabled. Even
if this is a bug that can be fixed, having two knobs for exactly the
same piece of hardware is confusing at the very least.


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2009-08-04 17:13:08

by Marcel Holtmann

[permalink] [raw]
Subject: Re: Multiple rfkill knobs for the same hardware interface

Hi Andrey,

> This is mostly the same situation as ACPI vs. platform backlight
> control. Here on Dell XPS M1330:
>
> {pts/1}% rfkill list
> 0: dell-wifi: Wireless LAN
> Soft blocked: no
> Hard blocked: no
> 1: dell-bluetooth: Bluetooth
> Soft blocked: no
> Hard blocked: no
> 2: phy0: Wireless LAN
> Soft blocked: no
> Hard blocked: no
> 4: hci0: Bluetooth
> Soft blocked: no
> Hard blocked: no
>
> Arguably, either one in the pair is redundant. Moreover, hard disabling
> wireless (using slider on notebook side):
>
> {pts/1}% rfkill list
> 0: dell-wifi: Wireless LAN
> Soft blocked: no
> Hard blocked: no
> 1: dell-bluetooth: Bluetooth
> Soft blocked: no
> Hard blocked: no
> 2: phy0: Wireless LAN
> Soft blocked: no
> Hard blocked: yes
>
> So dell-laptop actually lies claiming that both radios are enabled. Even
> if this is a bug that can be fixed, having two knobs for exactly the
> same piece of hardware is confusing at the very least.

this is clearly a bug in the dell-laptop module and it seems that
Matthew fixed that already.

The redundancy is just fine. The new RFKILL subsystem is capable of
handling it and we have OP_CHANGE_ALL for exactly this case. You either
wanna switch Bluetooth on or off. And with a 2.6.31 kernel you can do
exactly this and no longer have to bother with details of the RFKILL
switches representing Bluetooth for example.

Also while we would like to have the platform RFKILL switches mapping to
a device switch, it is in practice not possible since in most cases they
are using some kind of hotplug anyway.

Regards

Marcel



2009-08-04 12:43:47

by Matthew Garrett

[permalink] [raw]
Subject: Re: Multiple rfkill knobs for the same hardware interface

On Tue, Aug 04, 2009 at 04:29:56PM +0400, Andrey Borzenkov wrote:

> So dell-laptop actually lies claiming that both radios are enabled. Even
> if this is a bug that can be fixed, having two knobs for exactly the
> same piece of hardware is confusing at the very least.

I've sent a fix for this bug. However, the functionality isn't entirely
redundant. Control over the platform interface allows overriding of BIOS
settings.

--
Matthew Garrett | [email protected]