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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5C5DCC38A2D for ; Tue, 25 Oct 2022 09:25:16 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id BCCE210E2F0; Tue, 25 Oct 2022 09:25:14 +0000 (UTC) Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by gabe.freedesktop.org (Postfix) with ESMTPS id F075510E2E9 for ; Tue, 25 Oct 2022 09:25:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1666689912; x=1698225912; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=cZVdOL+Y/sIgt9URnXIc+Uzvf3DjHE6NPrlEW0X0vNQ=; b=lJ91JRcTnp0u95bDfJLBVJdgmOBZwmQnFtHadbPqUOVeTtChz2xZ82nR RSrnoahORYx4AoHd5xLd5ey990xhBV49Yaf7i4w2uTXzNvGpK7kF/u7GN dPC9iSA4k+I+uGREtjCRBF/6jk/kLBEwX/mMIakAVkFynOPbt8BwDeKMX IhhZKXS5FJUyAZFff7NKmk+WqOpQas/Zf6GwqMwMTqPu1XqgAVO9srqks RldKVKz3iWqp9arLUaY4tgLO7cb/1IJXBy8lyD0f6Ux0CC0i6atioy0jH ojHdEAvZK79BuWhXNzz7rn4x/p2Mw2CRMzK7QPTW8HKHv09OoeuyiwN3F Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10510"; a="371845971" X-IronPort-AV: E=Sophos;i="5.95,211,1661842800"; d="scan'208";a="371845971" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Oct 2022 02:25:11 -0700 X-IronPort-AV: E=McAfee;i="6500,9779,10510"; a="626362928" X-IronPort-AV: E=Sophos;i="5.95,211,1661842800"; d="scan'208";a="626362928" Received: from arybkin-mobl1.ccr.corp.intel.com (HELO intel.com) ([10.252.44.231]) by orsmga007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Oct 2022 02:25:09 -0700 Date: Tue, 25 Oct 2022 11:25:06 +0200 From: Andi Shyti To: "Dixit, Ashutosh" Message-ID: References: <20221024210953.1572998-1-gwan-gyeong.mun@intel.com> <87mt9kppb6.wl-ashutosh.dixit@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87mt9kppb6.wl-ashutosh.dixit@intel.com> Subject: Re: [Intel-gfx] [PATCH] drm/i915/hwmon: Fix a build error used with clang compiler X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: intel-gfx@lists.freedesktop.org, llvm@lists.linux.dev Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" Hi Ashutosh, > > drivers/gpu/drm/i915/i915_hwmon.c:115:16: error: result of comparison of constant 18446744073709551615 with expression of type 'typeof (_Generic((field_msk), char: (unsigned char)0, unsigned char: (unsigned char)0, signed char: (unsigned char)0, unsigned short: (unsigned short)0, short: (unsigned short)0, unsigned int: (unsigned int)0, int: (unsigned int)0, unsigned long: (unsigned long)0, long: (unsigned long)0, unsigned long long: (unsigned long long)0, long long: (unsigned long long)0, default: (field_msk)))' (aka 'unsigned int') is always false [-Werror,-Wtautological-constant-out-of-range-compare] > > What is 18446744073709551615? You may want to limit the length of this line > or checkpatch doesn't complain? yeah! I am not a clang user, and this must be some ugly error output. I don't think it makes sense to break it, though. > > bits_to_set = FIELD_PREP(field_msk, nval); > > ^~~~~~~~~~~~~~~~~~~~~~~~~~~ > > ./include/linux/bitfield.h:114:3: note: expanded from macro 'FIELD_PREP' > > __BF_FIELD_CHECK(_mask, 0ULL, _val, "FIELD_PREP: "); \ > > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > ./include/linux/bitfield.h:71:53: note: expanded from macro '__BF_FIELD_CHECK' > > BUILD_BUG_ON_MSG(__bf_cast_unsigned(_mask, _mask) > \ > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~ > > ./include/linux/build_bug.h:39:58: note: expanded from macro 'BUILD_BUG_ON_MSG' > > ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~ > > ./include/linux/compiler_types.h:357:22: note: expanded from macro 'compiletime_assert' > > _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) > > ~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > ./include/linux/compiler_types.h:345:23: note: expanded from macro '_compiletime_assert' > > __compiletime_assert(condition, msg, prefix, suffix) > > ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > ./include/linux/compiler_types.h:337:9: note: expanded from macro '__compiletime_assert' > > if (!(condition)) \ > > > > Fixes: 99f55efb7911 ("drm/i915/hwmon: Power PL1 limit and TDP setting") > > Cc: Ashutosh Dixit > > Cc: Anshuman Gupta > > Cc: Andi Shyti > > Signed-off-by: Gwan-gyeong Mun > > --- > > drivers/gpu/drm/i915/i915_hwmon.c | 12 +++--------- > > 1 file changed, 3 insertions(+), 9 deletions(-) > > > > diff --git a/drivers/gpu/drm/i915/i915_hwmon.c b/drivers/gpu/drm/i915/i915_hwmon.c > > index 9e9781493025..782a621b1928 100644 > > --- a/drivers/gpu/drm/i915/i915_hwmon.c > > +++ b/drivers/gpu/drm/i915/i915_hwmon.c > > @@ -101,21 +101,16 @@ hwm_field_read_and_scale(struct hwm_drvdata *ddat, i915_reg_t rgadr, > > > > static void > > hwm_field_scale_and_write(struct hwm_drvdata *ddat, i915_reg_t rgadr, > > - u32 field_msk, int nshift, > > - unsigned int scale_factor, long lval) > > + int nshift, unsigned int scale_factor, long lval) > > { > > u32 nval; > > - u32 bits_to_clear; > > - u32 bits_to_set; > > > > /* Computation in 64-bits to avoid overflow. Round to nearest. */ > > nval = DIV_ROUND_CLOSEST_ULL((u64)lval << nshift, scale_factor); > > > > - bits_to_clear = field_msk; > > - bits_to_set = FIELD_PREP(field_msk, nval); > > - > > hwm_locked_with_pm_intel_uncore_rmw(ddat, rgadr, > > - bits_to_clear, bits_to_set); > > + PKG_PWR_LIM_1, > > + FIELD_PREP(PKG_PWR_LIM_1, nval)); > > I don't want to give up so easily. We might have future uses for the > function where we want field_msk to be passed into the function (rather > than set inside the function as in this patch). > > Do we understand what clang is complaining about? And why this compiles > with gcc? Because we are not compiling the builtin functions with gcc but gcc has support for them. The FIELD_PREP checks if the first parameter is a constant: BUILD_BUG_ON_MSG(!__builtin_constant_p(_mask), where _mask was our field_mask, but we ignore it. Apparently clang doesn't. If we want to stick to gcc only, then I still think the patch is correct for two reasons: 1. it's cleaner 2. we would get on with the job and if one day we will decide to suppport builtin functions in gcc as well, we will sleep peacefully :) > Copying llvm@lists.linux.dev too. maybe llvm folks have a better opinion. Thanks, Andi > Thanks. > -- > Ashutosh > > > > } > > > > /* > > @@ -406,7 +401,6 @@ hwm_power_write(struct hwm_drvdata *ddat, u32 attr, int chan, long val) > > case hwmon_power_max: > > hwm_field_scale_and_write(ddat, > > hwmon->rg.pkg_rapl_limit, > > - PKG_PWR_LIM_1, > > hwmon->scl_shift_power, > > SF_POWER, val); > > return 0; > > -- > > 2.37.1 > >