linux-kernel - Re: [PATCH 4/8] rfkill: add read-write rfkill switch support

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Date:	Mon, 14 Apr 2008 20:06:50 +0100
From:	Carlos Corbacho <carlos@...angeworlds.co.uk>
To:	Ivo van Doorn <ivdoorn@...il.com>
Cc:	Henrique de Moraes Holschuh <hmh@....eng.br>,
	linux-kernel@...r.kernel.org,
	"John W. Linville" <linville@...driver.com>,
	Dmitry Torokhov <dtor@...l.ru>
Subject: Re: [PATCH 4/8] rfkill: add read-write rfkill switch support

On Monday 14 April 2008 13:00:41 Ivo van Doorn wrote:
> > > See rt2x00 and b43 in driver-wireless for an example implementation
> > > of pollable input device and rfkill
> >
> > They're broken by design, at least in b43's case.  Someone (Carlos, I
> > believe?) posted an example of a ping-pong scenario using b43.
>
> Thats true. But was that a scenario where there were 2 keys for the same
> radio type? Or was that a matter of the driver indicating a key pressed
> event while it has no attached key to it, and only checked the register for
> the key status and the current radio status and saw it was different?

Two part problem:

1) Bug in rfkill; rfkill is toggling all devices in the same state, and not 
actually checking the type.

(I submitted a patch for this on Sunday, although I sent it to linux-wireless 
before you sent the MAINTAINERS patch with netdev as the official list; but I 
did CC you on it regardless so you should have seen this. If not, let me know 
and I'll resend it).

2) The cycle-of-doom bug, as described earlier.

This still applies.

Yes, b43 can also be fixed not to emit a keycode if it cannot control the 
rfkill switch; but that doesn't solve the case of what happens if both the 
wireless driver and the platform driver can control the radio.

I agree wholeheartedly with Henrique here though - wireless drivers should 
_not_ be using key press events as a reporting mechanism.

-Carlos
-- 
E-Mail: carlos@...angeworlds.co.uk
Web: strangeworlds.co.uk
GPG Key ID: 0x23EE722D
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