linux-kernel - Re: [PATCH] platform/x86: thinkpad_acpi: fix for incorrect fan reporting on some ThinkPad systems

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Date:   Fri, 8 Dec 2023 13:06:17 +0200 (EET)
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     Vishnu Sankar <vishnuocv@...il.com>
cc:     Hans de Goede <hdegoede@...hat.com>,
        Mark Pearson <mpearson-lenovo@...ebb.ca>,
        platform-driver-x86@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>, markgross@...nel.org
Subject: Re: [PATCH] platform/x86: thinkpad_acpi: fix for incorrect fan
 reporting on some ThinkPad systems

On Fri, 8 Dec 2023, Ilpo Järvinen wrote:

> On Thu, 7 Dec 2023, Vishnu Sankar wrote:
> 
> Hi Vishnu,
> 
> Thanks for the patch.
> 
> > Some ThinkPad systems ECFW use non-standard addresses for fan control
> > and reporting. This patch adds support for such ECFW so that it can report
> > the correct fan values.
> > Tested on Thinkpads L13 Yoga Gen 2 and X13 Yoga Gen 2.
> > 
> > Co-developed-by: Mark Pearson <mpearson-lenovo@...ebb.ca>
> > Signed-off-by: Vishnu Sankar <vishnuocv@...il.com>

> > +		/* Default mode is AUTO which means controlled by EC */
> > +		if (unlikely(!acpi_ec_read(fan_status_offset_ns, &s)))
> 
> I'm skeptical that all these unlikely/likely() are useful. Some might even 
> be harmful if e.g. is some error condition keeps repeating itself and 
> the particular if handling that is marked with unlikely().
> 
> I know the code in that file is littered with them already but it would 
> be better to add into that, IMO.

So I'm missing the negative here, I meant: ... not add into that ...

-- 
 i.