Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1173127AbdDXP1n (ORCPT ); Mon, 24 Apr 2017 11:27:43 -0400 Received: from mail-it0-f66.google.com ([209.85.214.66]:34288 "EHLO mail-it0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1169980AbdDXP1b (ORCPT ); Mon, 24 Apr 2017 11:27:31 -0400 MIME-Version: 1.0 In-Reply-To: References: <1492780055-4892-1-git-send-email-daniel.baluta@nxp.com> <1492780055-4892-2-git-send-email-daniel.baluta@nxp.com> From: Arnd Bergmann Date: Mon, 24 Apr 2017 17:27:25 +0200 X-Google-Sender-Auth: rlKDz2glv_rNAZUNCSRHrTp1tQ8 Message-ID: Subject: Re: [alsa-devel] [PATCH 1/2] ASoC: codec: wm9860: avoid maybe-uninitialized warning To: Daniel Baluta Cc: Daniel Baluta , alsa-devel@alsa-project.org, Linux Kernel Mailing List , patches@opensource.wolfsonmicro.com, Takashi Iwai , Liam Girdwood , Mark Brown , Charles Keepax Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id v3OFRrmk016937 Content-Length: 5847 Lines: 133 On Mon, Apr 24, 2017 at 3:15 PM, Daniel Baluta wrote: > On Fri, Apr 21, 2017 at 5:46 PM, Arnd Bergmann wrote: >> On Fri, Apr 21, 2017 at 3:07 PM, Daniel Baluta wrote: >>> The new PLL configuration code triggers a harmless warning: >>> >>> sound/soc/codecs/wm8960.c: In function 'wm8960_configure_clocking': >>> sound/soc/codecs/wm8960.c:735:3: error: 'best_freq_out' may be used >>> uninitialized in this function [-Werror=maybe-uninitialized] >>> wm8960_set_pll(codec, freq_in, best_freq_out); >>> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >>> sound/soc/codecs/wm8960.c:699:12: note: 'best_freq_out' was declared >>> here >>> >>> Fixes: 84fdc00d519f ("ASoC: codec: wm9860: Refactor PLL out freq search") >>> Fixes: 303e8954af8d ("ASoC: codec: wm8960: Stop when a matching PLL freq is found") >>> Suggested-by: Arnd Bergmann >>> Signed-off-by: Daniel Baluta >>> --- >>> Arnd, >>> >>> I agree that your code was more both humans and gcc anyhow >>> for consistency with wm8960_configure_sysclk function I preferred >>> to keep the "if(..) break" statements. >> >> How about changing both functions the same way then? > > I've tried but I couldn't find any solution. For clarity here is how > the code actually looks like. > > The git diff is a little bit misleading. Here is how wm8960_configure_pll code > looks like: > > https://pastebin.com/naGdVNQz > > static > int wm8960_configure_pll(struct snd_soc_codec *codec, int freq_in, > » » » int *sysclk_idx, int *dac_idx, int *bclk_idx) > { > » struct wm8960_priv *wm8960 = snd_soc_codec_get_drvdata(codec); > » int sysclk, bclk, lrclk, freq_out; > » int diff, closest, best_freq_out; > » int i, j, k; > > » bclk = wm8960->bclk; > » lrclk = wm8960->lrclk; > » closest = freq_in; > > » best_freq_out = -EINVAL; > » *sysclk_idx = *dac_idx = *bclk_idx = -1; > > » for (i = 0; i < ARRAY_SIZE(sysclk_divs); ++i) { > » » if (sysclk_divs[i] == -1) > » » » continue; > » » for (j = 0; j < ARRAY_SIZE(dac_divs); ++j) { > » » » sysclk = lrclk * dac_divs[j]; > » » » freq_out = sysclk * sysclk_divs[i]; > > » » » for (k = 0; k < ARRAY_SIZE(bclk_divs); ++k) { > » » » » if (!is_pll_freq_available(freq_in, freq_out)) > » » » » » continue; > > » » » » diff = sysclk - bclk * bclk_divs[k] / 10; > » » » » if (diff == 0) { > » » » » » *sysclk_idx = i; > » » » » » *dac_idx = j; > » » » » » *bclk_idx = k; > » » » » » best_freq_out = freq_out; > » » » » » break; > » » » » } > » » » » if (diff > 0 && closest > diff) { > » » » » » *sysclk_idx = i; > » » » » » *dac_idx = j; > » » » » » *bclk_idx = k; > » » » » » closest = diff; > » » » » » best_freq_out = freq_out; > » » » » } > » » » } > » » » if (k != ARRAY_SIZE(bclk_divs)) > » » » » break; > » » } > » » if (j != ARRAY_SIZE(dac_divs)) > » » » break; > » } > > » return best_freq_out; > } > > In my opinion this is a compiler false positive. Any clue on how to rework this > would be welcomed :). I couldn't find any decent solution. Actually I think in this case the compiler is supposed to warn if best_freq_out is not initialized, as we would never set it in case is_pll_freq_available() returns false for all inputs or sysclk_divs[] is -1 for all fields. I'd leave the initialization then, and only replace the breaks with a goto (not tested): > » for (i = 0; i < ARRAY_SIZE(sysclk_divs); ++i) { > » » if (sysclk_divs[i] == -1) > » » » continue; > » » for (j = 0; j < ARRAY_SIZE(dac_divs); ++j) { > » » » sysclk = lrclk * dac_divs[j]; > » » » freq_out = sysclk * sysclk_divs[i]; > > » » » for (k = 0; k < ARRAY_SIZE(bclk_divs); ++k) { > » » » » if (!is_pll_freq_available(freq_in, freq_out)) > » » » » » continue; > > » » » » diff = sysclk - bclk * bclk_divs[k] / 10; > » » » » if (diff == 0) { > » » » » » *sysclk_idx = i; > » » » » » *dac_idx = j; > » » » » » *bclk_idx = k; > » » » » » best_freq_out = freq_out; > » » » » » goto out; > » » » » } > » » » » if (diff > 0 && closest > diff) { > » » » » » *sysclk_idx = i; > » » » » » *dac_idx = j; > » » » » » *bclk_idx = k; > » » » » » closest = diff; > » » » » » best_freq_out = freq_out; > » » » » } > » » » } > » » } > » } >out: > » return best_freq_out; > } Arnd