From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753579AbaHKRul (ORCPT ); Mon, 11 Aug 2014 13:50:41 -0400 Received: from mail-pd0-f179.google.com ([209.85.192.179]:47873 "EHLO mail-pd0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752150AbaHKRuk (ORCPT ); Mon, 11 Aug 2014 13:50:40 -0400 Date: Mon, 11 Aug 2014 10:50:36 -0700 From: Brian Norris To: Geert Uytterhoeven Cc: Boris BREZILLON , linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mtd: nand: Use ULL-suffix for big u64 constant Message-ID: <20140811175036.GU3711@ld-irv-0074> References: <1407604073-7484-1-git-send-email-geert@linux-m68k.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1407604073-7484-1-git-send-email-geert@linux-m68k.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Aug 09, 2014 at 07:07:53PM +0200, Geert Uytterhoeven wrote: > drivers/mtd/nand/nand_timings.c:45: warning: integer constant is too large for ‘long’ type On what compiler / static analyzer? > Signed-off-by: Geert Uytterhoeven > --- > drivers/mtd/nand/nand_timings.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/mtd/nand/nand_timings.c b/drivers/mtd/nand/nand_timings.c > index 8b36253420fa..e81470a8ac67 100644 > --- a/drivers/mtd/nand/nand_timings.c > +++ b/drivers/mtd/nand/nand_timings.c > @@ -42,7 +42,7 @@ static const struct nand_sdr_timings onfi_sdr_timings[] = { > .tRHZ_max = 200000, > .tRLOH_min = 0, > .tRP_min = 50000, > - .tRST_max = 250000000000, > + .tRST_max = 250000000000ULL, See [1] and [2]. I'm pretty sure it is a bug in your tool to warn about this. The C standard seems pretty clear that the large literal constant is automatically promoted to a sufficiently large type, so AIUI there should be no need for such a warning. A standards-compliant compiler will do the right thing. It really seems like this type of warning is only appropriate where a smaller literal constant is immediately operated on such that it will overflow. e.g.: .tRST_max = 250 * 1000 * 1000 * 1000, But this usually results in a different type of (correct) warning, like: warning: integer overflow in expression [-Woverflow] However, I could be convinced to apply this, if only to satisfy broken tools and to avoid addressing this question over and over... > .tWB_max = 200000, > .tRR_min = 40000, > .tWC_min = 100000, Brian [1] http://lists.infradead.org/pipermail/linux-mtd/2014-July/054750.html [2] http://lists.infradead.org/pipermail/linux-arm-kernel/2014-April/252494.html