From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 26F70C433EF for ; Fri, 25 Mar 2022 15:08:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344456AbiCYPKS (ORCPT ); Fri, 25 Mar 2022 11:10:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44636 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1359784AbiCYPKJ (ORCPT ); Fri, 25 Mar 2022 11:10:09 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 558F7DBD18; Fri, 25 Mar 2022 08:07:48 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id F3DE3B82833; Fri, 25 Mar 2022 15:07:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 24EC0C340E9; Fri, 25 Mar 2022 15:07:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1648220865; bh=JCOVLHohscIa00QIH1ZFiQHu3Zt5Fac47pp88wkyeaI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VBegQJ0vNjzPXPW9DmTFkm5pVsFkPYNj2yUGX1sIi/4o+laVA0lcLstbvV/YtZq40 4rbGYTmgw5CDknoMZuMEZ1XAC5mj/vAsGJLJ+ySZuhqRTeZc5JvvZ0oHn5tew3arMo jVieTeUxArosyZkHhlMG/K3IZth6e3zF9ibjhHus= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Giacomo Guiduzzi , Paolo Valente , Takashi Iwai Subject: [PATCH 5.4 15/29] ALSA: pci: fix reading of swapped values from pcmreg in AC97 codec Date: Fri, 25 Mar 2022 16:04:55 +0100 Message-Id: <20220325150419.025542374@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220325150418.585286754@linuxfoundation.org> References: <20220325150418.585286754@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Giacomo Guiduzzi commit 17aaf0193392cb3451bf0ac75ba396ec4cbded6e upstream. Tests 72 and 78 for ALSA in kselftest fail due to reading inconsistent values from some devices on a VirtualBox Virtual Machine using the snd_intel8x0 driver for the AC'97 Audio Controller device. Taking for example test number 72, this is what the test reports: "Surround Playback Volume.0 expected 1 but read 0, is_volatile 0" "Surround Playback Volume.1 expected 0 but read 1, is_volatile 0" These errors repeat for each value from 0 to 31. Taking a look at these error messages it is possible to notice that the written values are read back swapped. When the write is performed, these values are initially stored in an array used to sanity-check them and write them in the pcmreg array. To write them, the two one-byte values are packed together in a two-byte variable through bitwise operations: the first value is shifted left by one byte and the second value is stored in the right byte through a bitwise OR. When reading the values back, right shifts are performed to retrieve the previously stored bytes. These shifts are executed in the wrong order, thus reporting the values swapped as shown above. This patch fixes this mistake by reversing the read operations' order. Signed-off-by: Giacomo Guiduzzi Signed-off-by: Paolo Valente Cc: Link: https://lore.kernel.org/r/20220322200653.15862-1-guiduzzi.giacomo@gmail.com Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- sound/pci/ac97/ac97_codec.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/sound/pci/ac97/ac97_codec.c +++ b/sound/pci/ac97/ac97_codec.c @@ -938,8 +938,8 @@ static int snd_ac97_ad18xx_pcm_get_volum int codec = kcontrol->private_value & 3; mutex_lock(&ac97->page_mutex); - ucontrol->value.integer.value[0] = 31 - ((ac97->spec.ad18xx.pcmreg[codec] >> 0) & 31); - ucontrol->value.integer.value[1] = 31 - ((ac97->spec.ad18xx.pcmreg[codec] >> 8) & 31); + ucontrol->value.integer.value[0] = 31 - ((ac97->spec.ad18xx.pcmreg[codec] >> 8) & 31); + ucontrol->value.integer.value[1] = 31 - ((ac97->spec.ad18xx.pcmreg[codec] >> 0) & 31); mutex_unlock(&ac97->page_mutex); return 0; }