From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754904Ab3LSR3S (ORCPT ); Thu, 19 Dec 2013 12:29:18 -0500 Received: from cantor2.suse.de ([195.135.220.15]:33207 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751983Ab3LSR3K (ORCPT ); Thu, 19 Dec 2013 12:29:10 -0500 Date: Thu, 19 Dec 2013 18:29:09 +0100 Message-ID: From: Takashi Iwai To: Lee Jones Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linus.walleij@linaro.org, broonie@kernel.org, alsa-devel@alsa-project.org Subject: Re: [PATCH 02/11] ASoC: ab8500: Revert back to find_next_bit() In-Reply-To: <20131219164824.GA16145@lee--X1> References: <1387468508-12286-1-git-send-email-lee.jones@linaro.org> <1387468508-12286-3-git-send-email-lee.jones@linaro.org> <20131219164824.GA16145@lee--X1> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 Emacs/24.3 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org At Thu, 19 Dec 2013 16:48:24 +0000, Lee Jones wrote: > > > > Commit '166a34d ASoC: ab8500: Fix invalid cast to long pointer' > > > rather carelessly converts find_next_bit() to fls() (find last > > > bit set), which are not the same. > > > > Does it break on the real machines? > > It does, that's how I found the bug. > > > fls() behaves differently from find_next_bit(), of course, but in this > > case, it should work same in the end, since there are at most two > > bits. > > Unfortunately it doesn't work at all. This patch brings audio back to > a working state. It took me the best part of a day to track down the > issue. :( Hmm, then isn't the original code rather buggy? Check the values set there by ffs(), fls() and the original find_next_bit(), especially whether find_next_bit() gives a valid value fitting with the mask bits. Takashi