linux-kernel - Re: [PATCH][drivers/misc/thinkpad_acpi.c] duplicate test if (level & TP_EC_FAN

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Message-Id: <200802070117.45119.lenb@kernel.org>
Date:	Thu, 7 Feb 2008 01:17:44 -0500
From:	Len Brown <lenb@...nel.org>
To:	Roel Kluin <12o3l@...cali.nl>
Cc:	Roland Dreier <rdreier@...co.com>, len.brown@...el.com,
	ibm-acpi@....eng.br, ibm-acpi-devel@...ts.sourceforge.net,
	linux-acpi@...r.kernel.org, lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH][drivers/misc/thinkpad_acpi.c] duplicate test if (level & TP_EC_FAN_FULLSPEED)

Applied.

thanks,
-Len

On Monday 04 February 2008 18:24, Roel Kluin wrote:
> Roland Dreier wrote:
> >  >                 /* safety net should the EC not support AUTO
> >  >                  * or FULLSPEED mode bits and just ignore them */
> >  >                 if (level & TP_EC_FAN_FULLSPEED)
> >  >                         level |= 7;     /* safety min speed 7 */
> >  >                 else if (level & TP_EC_FAN_FULLSPEED)
> >  >                         level |= 4;     /* safety min speed 4 */
> >  > 
> >  > Note the duplicate test 'if (level & TP_EC_FAN_FULLSPEED)'. should
> >  > this be replaced by
> > 
> > Actually I suspect one of the two tests should be against TP_EC_FAN_AUTO
> > (based on the comment).
> > 
> 
> Thanks Roland, for your info
> 
> based on the comments in commit eaa7571b2d1a08873e4bdd8e6db3431df61cd9ad,
> I think this should be modified like below:
> 
> ACPI: thinkpad-acpi: add a safety net for TPEC fan control mode
> The Linux ThinkPad community is not positive that all ThinkPads that do
> HFSP EC fan control do implement full-speed and auto modes, some of the
> earlier ones supporting HFSP might not.
> 
> If the EC ignores the AUTO or FULL-SPEED bits, it will pay attention to the
> lower three bits that set the fan level. And as thinkpad-acpi was leaving
> these set to zero, it would stop(!) the fan, which is Not A Good Thing.
> So, as a safety net, we now make sure to also set the fan level part of the
> HFSP register to speed 7 for full-speed, and a minimum of speed 4 for auto
> mode.
> --
> second TP_EC_FAN_FULLSPEED should be P_EC_FAN_AUTO
> 
> 
> Signed-off-by: Roel Kluin <12o3l@...cali.nl>
> ---
> diff --git a/drivers/misc/thinkpad_acpi.c b/drivers/misc/thinkpad_acpi.c
> index cf56647..3c323fe 100644
> --- a/drivers/misc/thinkpad_acpi.c
> +++ b/drivers/misc/thinkpad_acpi.c
> @@ -4138,7 +4138,7 @@ static int fan_set_level(int level)
>  		 * or FULLSPEED mode bits and just ignore them */
>  		if (level & TP_EC_FAN_FULLSPEED)
>  			level |= 7;	/* safety min speed 7 */
> -		else if (level & TP_EC_FAN_FULLSPEED)
> +		else if (level & TP_EC_FAN_AUTO)
>  			level |= 4;	/* safety min speed 4 */
>  
>  		if (!acpi_ec_write(fan_status_offset, level))
> 
> --
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