From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932230AbbGGPsN (ORCPT ); Tue, 7 Jul 2015 11:48:13 -0400 Received: from mga01.intel.com ([192.55.52.88]:2151 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757458AbbGGPsG (ORCPT ); Tue, 7 Jul 2015 11:48:06 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.15,424,1432623600"; d="scan'208";a="757646797" Message-ID: <1436284082.10819.56.camel@linux.intel.com> Subject: Re: [PATCH v3 1/7] clk: introduce clk_div_mask() helper From: Andy Shevchenko To: Stephen Boyd Cc: linux-kernel@vger.kernel.org, Sascha Hauer , Peter De Schrijver , Tero Kristo , Russell King , Dinh Nguyen Date: Tue, 07 Jul 2015 18:48:02 +0300 In-Reply-To: <20150618194815.GK29640@codeaurora.org> References: <1427822547-163289-1-git-send-email-andriy.shevchenko@linux.intel.com> <1427822547-163289-2-git-send-email-andriy.shevchenko@linux.intel.com> <20150618194815.GK29640@codeaurora.org> Organization: Intel Finland Oy Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.16.3-1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2015-06-18 at 12:48 -0700, Stephen Boyd wrote: > On 03/31, Andy Shevchenko wrote: > > diff --git a/include/linux/clk-provider.h b/include/linux/clk > > -provider.h > > index 5591ea7..20b0b67 100644 > > --- a/include/linux/clk-provider.h > > +++ b/include/linux/clk-provider.h > > @@ -353,6 +353,11 @@ struct clk_divider { > > spinlock_t *lock; > > }; > > > > +static inline unsigned long clk_div_mask(u8 width) > > +{ > > + return (1 << width) - 1; > > +} > > + > > Why not just change drivers to use GENMASK? It's a proven and > tested way to generate a bitmask. Too many unneeded calculations I suppose. Compare: mask = clk_div_mask(mm) << ms; which is simple ((1 << mm) - 1) << ms and mask = GENMASK(mm + ms - 1, ms); which is (~0 << ms) & (~0 >> (BITS_PER_LONG - 1 - (mm + ms - 1))) > > So I'd rather see drivers converted to use that macro directly > especially because the mask may need to start at some bit that > isn't 0. If you think the above is not a burden, I can do the conversion to GENMASK. Though it might make sense when ms = 0 explicitly. -- Andy Shevchenko Intel Finland Oy