From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jonathan Woithe Subject: Re: [PATCH 1/7] platform/x86: fujitsu-laptop: Define constants for FUNC operations Date: Sun, 4 Mar 2018 15:38:13 +1030 Message-ID: <20180304050813.GA3129@marvin.atrad.com.au> References: <20180227211539.5708-1-kernel@kempniu.pl> <20180227211539.5708-2-kernel@kempniu.pl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Andy Shevchenko Cc: Micha?? K??pie?? , Darren Hart , Andy Shevchenko , Platform Driver , Linux Kernel Mailing List List-Id: platform-driver-x86.vger.kernel.org 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?? 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? There is a lack of apparent consistency in the numeric mapping; for example, OP_SET_EXT includes the OP_SET bit, but OP_GET_EXT does not include the OP_GET bit. However, after inspecting the code I think this is simply reflecting what the hardware expects. > And plain 0 doesn't look right in this concept (something like (0 << > 0) would probably do it). Given that all other definitions are in terms of BIT(), to my eye "(0 << 0)" looks as much out of place as plain "0". However, if the convention in this case would be to use the former then I have no objections. I presume the "(0 << 0)" idea comes from the fact that BIT() ultimately expands to some form of shift. Regards jonathan