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From: "John W. Linville" <>
To: Stanislaw Gruszka <>
Cc:, Zhu Yi <>,
	Reinette Chatre <>,
Subject: Re: [PATCH 2.6.30] iwl3945: fix rfkill switch
Date: Tue, 4 Aug 2009 08:49:51 -0400	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Tue, Aug 04, 2009 at 02:35:50PM +0200, Stanislaw Gruszka wrote:
> Due to rfkill and iwlwifi mishmash of SW / HW killswitch representation,
> we have race conditions which make unable turn wifi radio on, after enable
> and disable again killswitch. I can observe this problem on my laptop
> with iwl3945 device.
> In rfkill core HW switch and SW switch are separate 'states'. Device can
> RFKILL_STATE_HARD_BLOCKED. Whereas in iwlwifi driver we have separate bits
> STATUS_RF_KILL_HW and STATUS_RF_KILL_SW for HW and SW switches - radio can be
> turned on, only if both bits are cleared.
> In this particular race conditions, radio can not be turned on if in driver
> STATUS_RF_KILL_SW bit is set, and rfkill core is in state
> RFKILL_STATE_HARD_BLOCKED, because rfkill core is unable to call
> rfkill->toggle_radio(). This situation can be entered in case:
> - killswitch is turned on
> - rfkill core 'see' button change first and move to RFKILL_STATE_SOFT_BLOCKED
>   also call ->toggle_radio() and STATE_RF_KILL_SW in driver is set
> - iwl3945 get info about button from hardware to set STATUS_RF_KILL_HW bit and
>   force rfkill to move to RFKILL_STATE_HARD_BLOCKED
> - killsiwtch is turend off
> - driver clear STATUS_RF_KILL_HW
> - rfkill core is unable to clear STATUS_RF_KILL_SW in driver
> Additionally call to rfkill_epo() when STATUS_RF_KILL_HW in driver is set
> cause move to the same situation.
> In 2.6.31 this problem is fixed due to _total_ rewrite of rfkill subsystem.
> This is a quite small fix for 2.6.30.x in iwl3945 driver. We disable
> STATUS_RF_KILL_SW bit regardless of HW bit state. Also report to rfkill
> subsystem SW switch bit before HW switch bit to move rfkill subsystem
> to SOFT_BLOCK rather than HARD_BLOCK.
> Signed-off-by: Stanislaw Gruszka <>
> ---
> I'm not sure if this is good candidate for stable as this is not backport
> of upstream commit. Also I did not test this patch with other iwlwifi devices,
> only with iwl3945.

stable is about the only place it can go, since it fixes a problem
that doesn't exist in 2.6.31...

John W. Linville		Someday the world will need a hero, and you			might be all we have.  Be ready.
			¡Viva Honduras Libre!

  reply	other threads:[~2009-08-04 13:01 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-08-04 12:35 [PATCH 2.6.30] iwl3945: fix rfkill switch Stanislaw Gruszka
2009-08-04 12:49 ` John W. Linville [this message]
2009-08-05 21:07   ` [stable] " Greg KH
2009-08-05 22:51 ` reinette chatre
2009-08-06  7:19   ` Stanislaw Gruszka
2009-08-06 20:15     ` reinette chatre
2009-08-07  6:31       ` Stanislaw Gruszka
2009-08-10 16:44         ` reinette chatre
2009-08-11 14:09           ` Stanislaw Gruszka
2009-08-11 18:08             ` reinette chatre
2009-08-12 15:12               ` Stanislaw Gruszka
2009-08-12 16:45                 ` reinette chatre
2009-08-13  7:28                   ` Stanislaw Gruszka
2009-08-13  7:31             ` Stanislaw Gruszka

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