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 1A82CC433EF for ; Thu, 30 Dec 2021 12:30:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239238AbhL3M37 (ORCPT ); Thu, 30 Dec 2021 07:29:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41198 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235404AbhL3M36 (ORCPT ); Thu, 30 Dec 2021 07:29:58 -0500 Received: from mail-wr1-x433.google.com (mail-wr1-x433.google.com [IPv6:2a00:1450:4864:20::433]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C094DC061574 for ; Thu, 30 Dec 2021 04:29:57 -0800 (PST) Received: by mail-wr1-x433.google.com with SMTP id i22so50100966wrb.13 for ; Thu, 30 Dec 2021 04:29:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=message-id:date:mime-version:user-agent:subject:content-language:to :cc:references:from:in-reply-to:content-transfer-encoding; bh=O0+J3hfYi+tJOX87FRscUIQ71ohxgIJHCX2HAI7b8Uk=; b=WMadPGKQYElHu5jMUqicwQrvbZw0wasy3D2dwh6uxHrjnJIKPJU2olLLJiUHlD3145 plls98wtenzGF2fKfmdY+zgaoa+jfm1UcyH2wkz5HwMtk+9/Qh9TIqO85tG2dg+DB6lC +3e+sFx8vK+EaZzrlOQ4oMNMl7NxCcMoBoZJDv9wivx7eB6ftjYEV3iYCqcuggnraFTV AG6lYgy2JNYCSPoWhUz1P8FK3E5ws6ZBZTMb1uJZTczp3CiqAHm9U46gHeH3dcpnqQIH 1tS9OsNRcHYpfa4tH+NupuN9/QJu3+dM2VWCPAjJH1oxL2Qu9yUuX6I/dXc6pxLQ1KOy 0KTA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=O0+J3hfYi+tJOX87FRscUIQ71ohxgIJHCX2HAI7b8Uk=; b=u67xhKN/MraJwNNzcAnp5Ah2fzsfPijBkzDCbEcCmEdqndkVeSeIpCFhcVPN93xtCj DbuxPjJlb78Jz8R/65zEv+gj3iLR7fuZxgNx3a29EmGybcRf8gGG4KQPXe5zYZCt4a9K 3TUIXi2dDDrF1UsBnrwECVC4+3V6ggmKP/C+GK6z8hvhvp4I+LOTep/mV1VWUXNdGjBx sepiqFghOoAYMswSdo9uY6BwQKtyJkyWH9bwJWhxF+orNd0fR8np0tFyCzt/zZh53PyO BuM3QLEWvJHh6dOqM8nCC4hcXsTjt5GolWmEu1dkT8Z+4mbbr0Gxpa0i8SgO8zhHyPZ0 uJ9A== X-Gm-Message-State: AOAM531yWAlHjDmq02RgnuQjAEwNraDfk3PRUckZpfDtperKBmJ0uA4j eo8IxfUN9GGHEI/vzTe20EQ= X-Google-Smtp-Source: ABdhPJyeMdqRs+cOsnbASw7H4TcBciKWFlGxLhfRAl5VE2g8s7FE8D4hxsDXVPloniZ7EO3XL58Fpg== X-Received: by 2002:a5d:4385:: with SMTP id i5mr24410955wrq.178.1640867396353; Thu, 30 Dec 2021 04:29:56 -0800 (PST) Received: from [192.168.2.177] ([207.188.161.251]) by smtp.gmail.com with ESMTPSA id o12sm23945584wrv.76.2021.12.30.04.29.55 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 30 Dec 2021 04:29:55 -0800 (PST) Message-ID: Date: Thu, 30 Dec 2021 13:29:54 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Subject: Re: [PATCH v3] drm/mediatek: Fix unused-but-set variable warning Content-Language: en-US To: Miles Chen , Chun-Kuang Hu , Philipp Zabel , David Airlie , Daniel Vetter , Nathan Chancellor , Nick Desaulniers , Jie Qiu , Junzhi Zhao Cc: Zhiqiang Lin , CK Hu , dri-devel@lists.freedesktop.org, linux-mediatek@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev References: <20211230093610.28012-1-miles.chen@mediatek.com> From: Matthias Brugger In-Reply-To: <20211230093610.28012-1-miles.chen@mediatek.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 30/12/2021 10:36, Miles Chen wrote: > clang reports a unused-but-set variable warning: > drivers/gpu/drm/mediatek/mtk_cec.c:85:6: warning: variable 'tmp' set but not used [-Wunused-but-set-variable] > > In current implementation, mtk_cec_mask() writes val into target register > and ignores the mask. After talking to our hdmi experts, mtk_cec_mask() > should read a register, clean only mask bits, and update (val | mask) bits > to the register. > > Fixes: 8f83f26891e1 ("drm/mediatek: Add HDMI support") > > Cc: Zhiqiang Lin > Cc: CK Hu > Cc: Matthias Brugger > > Signed-off-by: Miles Chen I'm still not happy with the commit subject, I think it is misleading. Clang only helped to find the bug, but the we are fixing something else, that's not just a clang warning. But I don't want to nit-pick too much so: Reviewed-by: Matthias Brugger > > --- > > Change since v1: > add Fixes tag > > Change since v2: > add explanation of mtk_cec_mask() > > Change-Id: Iec6402b0532942f4d0e8bc56817eb87b95c03fad > --- > drivers/gpu/drm/mediatek/mtk_cec.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/mediatek/mtk_cec.c b/drivers/gpu/drm/mediatek/mtk_cec.c > index e9cef5c0c8f7..cdfa648910b2 100644 > --- a/drivers/gpu/drm/mediatek/mtk_cec.c > +++ b/drivers/gpu/drm/mediatek/mtk_cec.c > @@ -85,7 +85,7 @@ static void mtk_cec_mask(struct mtk_cec *cec, unsigned int offset, > u32 tmp = readl(cec->regs + offset) & ~mask; > > tmp |= val & mask; > - writel(val, cec->regs + offset); > + writel(tmp, cec->regs + offset); > } > > void mtk_cec_set_hpd_event(struct device *dev, >