From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andy Shevchenko Subject: Re: [RESEND PATCH v4 1/8] bitops: Introduce the for_each_set_clump macro Date: Thu, 4 Oct 2018 15:10:46 +0300 Message-ID: <20181004121046.GT15943@smile.fi.intel.com> References: <40ecad49-2797-0d30-b52d-a2e6838dc1ab@rasmusvillemoes.dk> <20181002082142.GC15943@smile.fi.intel.com> <20181003114804.GE15943@smile.fi.intel.com> <20181004103620.GB4779@icarus> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20181004103620.GB4779@icarus> Sender: linux-kernel-owner@vger.kernel.org To: William Breathitt Gray Cc: Rasmus Villemoes , linus.walleij@linaro.org, akpm@linux-foundation.org, linux-gpio@vger.kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, Arnd Bergmann List-Id: linux-gpio@vger.kernel.org On Thu, Oct 04, 2018 at 07:36:20PM +0900, William Breathitt Gray wrote: > On Wed, Oct 03, 2018 at 02:48:04PM +0300, Andy Shevchenko wrote: > > On Tue, Oct 02, 2018 at 11:21:42AM +0300, Andy Shevchenko wrote: > > > > > I would rather go with two prototypes to get()/set() a clump in the bitmap > > > in a way when it's aligned and BITS_PER_LONG % clump_size == 0. > > > > To make things much easier, restrict clump_size to the one > > from the following set: > > > > 1, 2, 4, 8, 16, 32 even on 64-bit platforms. > > > > If it would be simpler solution to add 64 here (implying 32-bit platform), > > I would vote for that. > > > > For the generic case we might need something like: > > > > unsigned long bitmap_get_bits(unsigned long *src, unsigned int start, unsigned int nbits) > > { > > assert(nbits > BITS_PER_LONG); > > > > /* Something like Rasmus proposed earlier */ > > } > > > > And similar to setter. > > > > > > -- > > With Best Regards, > > Andy Shevchenko > > I have no objections to have a simplier macro for these common clump > sizes -- afterall, I suspect most drivers will likely use clump sizes > that are powers of 2 anyway. It would be nice to have a more versatile > macro though for those drivers that would benefit from odd clump sizes, > but we can perhaps postpone that until the need arises (the GPIO drivers > in this patchset all use a power of 2). Yes, this is my point of view: don't produce additional complexity to some which has no users (yet). When we would really have groups out of an odd bit number, we may reconsider. -- With Best Regards, Andy Shevchenko