linux-kernel - Re: [PATCH 1/7] platform/x86: fujitsu-laptop: Define constants for FUNC operations

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Date:   Mon, 5 Mar 2018 15:16:50 -0800
From:   Darren Hart <dvhart@...radead.org>
To:     Michał Kępień <kernel@...pniu.pl>
Cc:     Jonathan Woithe <jwoithe@...t42.net>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Andy Shevchenko <andy@...radead.org>,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/7] platform/x86: fujitsu-laptop: Define constants for
 FUNC operations

On Sun, Mar 04, 2018 at 08:44:26PM +0100, Michał Kępień wrote:
> > On Wed, Feb 28, 2018 at 06:08:52PM +0200, Andy Shevchenko wrote:
> > > On Tue, Feb 27, 2018 at 11:15 PM, Micha?? K??pie?? <kernel@...pniu.pl> wrote:
> > > > Various functions exposed by the firmware through the FUNC interface
> > > > tend to use a consistent set of integers for denoting the type of
> > > > operation to be performed for a specified feature.  Use named constants
> > > > instead of integers in each call_fext_func() invocation in order to more
> > > > clearly convey the intent of each call.
> > > >
> > > > Note that FUNC_FLAGS is a bit peculiar:
> > > 
> > > > +/* FUNC interface - operations */
> > > > +#define OP_GET                         BIT(1)
> > > > +#define OP_GET_CAPS                    0
> > > > +#define OP_GET_EVENTS                  BIT(0)
> > > > +#define OP_GET_EXT                     BIT(2)
> > > > +#define OP_SET                         BIT(0)
> > > > +#define OP_SET_EXT                     (BIT(2) | BIT(0))
> > > 
> > > Hmm... this looks unordered a bit.
> > 
> > It seems to be ordered alphabetically on the identifier.  Andy, is it
> > preferred to order defines like this based on resolved numeric order?
>  
> Just to expand on what Jonathan wrote above: if you take a peek at the
> end result of the patch series, you will notice a pattern: constants in
> each section are ordered alphabetically by their name.  I wanted all
> sections to be consistently ordered.  If you would rather have me order
> things by the bit index, sure, no problem, just please note that the
> order above is not accidental.

Hrm. In my experience it is more typical to order by value (bit), that's a
little less obvious when using the BIT()|BIT() macros though. So long as it's
consistent, I think that's what matters most.

-- 
Darren Hart
VMware Open Source Technology Center