linux-kernel - Re: [PATCH] dell-smm-hwmon: Cache fan_type() calls and use fan

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Message-ID: <20160527094736.GL29844@pali>
Date:	Fri, 27 May 2016 11:47:36 +0200
From:	Pali Rohár <pali.rohar@...il.com>
To:	Thorsten Leemhuis <fedora@...mhuis.info>
Cc:	Jan C Peters <jcpeters89@...il.com>,
	David Santamaría Rogado <howl.nsp@...il.com>,
	Peter Saunderson <peteasa@...il.com>,
	Jean Delvare <jdelvare@...e.com>,
	Guenter Roeck <linux@...ck-us.net>,
	Tolga Cakir <cevelnet@...il.com>, linux-hwmon@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] dell-smm-hwmon: Cache fan_type() calls and use
 fan_status() for fan detection

On Friday 27 May 2016 10:00:05 Thorsten Leemhuis wrote:
> Pali Rohár wrote on 26.05.2016 17:51:
> > On Thursday 26 May 2016 17:39:57 Thorsten Leemhuis wrote:
> >> > I need to know if this patch fixes problem on Dell Studio XPS 8000
> >> > and Dell Studio XPS 8100 machines, so we can revert git commits:
> >> > 6220f4ebd7b4 ("hwmon: (dell-smm) Blacklist Dell Studio XPS 8000")
> >> > a4b45b25f18d ("hwmon: (dell-smm) Blacklist Dell Studio XPS 8100")
> >> Just checked: Sorry, that patch did not fix the CPU fan speed issue
> >> on my XPS 8000, so there is afaics no reason to revert 6220f4ebd7b4
> >> :-/
> > Please, can you apply patch "dell-smm-hwmon: In debug mode log duration 
> > of SMM calls" 
> 
> On top of "Cache fan_type() calls and use fan_status() for fan 
> detection" or with that patch reverted? I did the latter and 
> tested with 4.6 (just mentioning it here in case it matters).

Ideally both.

> > and compile dell-smm-hwmon in debug mode to tell us which 
> > SMM call takes too long? This is probably they key for that XPS 
> > problems...
> 
> [    5.941037] dell_smm_hwmon: smm(0xfea3 0x0000) = 0x4147  (took   14470 usecs)
> [    5.941139] dell_smm_hwmon: smm(0x11a3 0x0000) = 0xffff  (took      93 usecs)
> [    5.941236] dell_smm_hwmon: smm(0x11a3 0x0001) = 0xffff  (took      93 usecs)
> [    5.941331] dell_smm_hwmon: smm(0x11a3 0x0002) = 0xffff  (took      92 usecs)
> [    5.941427] dell_smm_hwmon: smm(0x11a3 0x0003) = 0xffff  (took      92 usecs)
> [    5.941526] dell_smm_hwmon: smm(0x03a3 0x0000) = 0x0000  (took      95 usecs)
> [    5.941625] dell_smm_hwmon: smm(0x03a3 0x0001) = 0x0001  (took      95 usecs)
> 
> HTH, CU, knurd

I do not see any long taking SMM call here. Are you really sure that
your machine freeze when loading or using dell-smm-hwmon?

-- 
Pali Rohár
pali.rohar@...il.com