linux-kernel - Re: [PATCH RESEND] iwlwifi, Do not implement thermal zone unless ucode is loaded

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Message-ID: <57861172.30103@redhat.com>
Date:	Wed, 13 Jul 2016 06:01:22 -0400
From:	Prarit Bhargava <prarit@...hat.com>
To:	Kalle Valo <kvalo@...eaurora.org>
CC:	"Grumbach, Emmanuel" <emmanuel.grumbach@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linuxwifi <linuxwifi@...el.com>,
	"Coelho, Luciano" <luciano.coelho@...el.com>,
	"Berg, Johannes" <johannes.berg@...el.com>,
	"Ivgi, Chaya Rachel" <chaya.rachel.ivgi@...el.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"Sharon, Sara" <sara.sharon@...el.com>,
	"linux-wireless@...r.kernel.org" <linux-wireless@...r.kernel.org>
Subject: Re: [PATCH RESEND] iwlwifi, Do not implement thermal zone unless
 ucode is loaded



On 07/13/2016 02:50 AM, Kalle Valo wrote:
> Prarit Bhargava <prarit@...hat.com> writes:
> 
>>> We implement thermal zone because we do support it, but the problem is
>>> that we need the firmware to be loaded for that. So you can argue that
>>> we should register *later* when the firmware is loaded. But this is
>>> really not helping all that much because the firmware can also be
>>> stopped at any time. So you'd want us to register / unregister the
>>> thermal zone anytime the firmware is loaded / unloaded?
>>
>> You might have to do that.  I think that if the firmware enables a feature then
>> the act of loading the firmware should run the code that enables the feature.
>> IMO of course.
> 
> But I suspect that the iwlwifi firmware is loaded during interface up
> (and unloaded during interface down) and in that case
> register/unregister would be happening all the time. 

You make it sound like the interface is coming and going a 1000 times a second.
 Maybe this happens once during runtime & during suspend/resume cycles?  What
about the cases when the firmware isn't present (and that's what lead me to this
bug)?

That doesn't sound
> like a good idea. I would rather try to fix the thermal interface to
> handle the cases when the measurement is not available.
> 

Userspace is broken because of this change.  I've had to make another horrible
change to cpufreq for a similar change so I don't see the argument here to just
blame userspace and ignore the outcome of the patch.

P.