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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 74026C433F5 for ; Tue, 26 Oct 2021 09:13:52 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 2E49F60187 for ; Tue, 26 Oct 2021 09:13:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 2E49F60187 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id A527C6E413; Tue, 26 Oct 2021 09:13:51 +0000 (UTC) Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by gabe.freedesktop.org (Postfix) with ESMTPS id 1DA4D6E41D for ; Tue, 26 Oct 2021 09:13:50 +0000 (UTC) X-IronPort-AV: E=McAfee;i="6200,9189,10148"; a="293321966" X-IronPort-AV: E=Sophos;i="5.87,182,1631602800"; d="scan'208";a="293321966" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Oct 2021 02:13:49 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.87,182,1631602800"; d="scan'208";a="497232820" Received: from stinkbox.fi.intel.com (HELO stinkbox) ([10.237.72.171]) by orsmga008.jf.intel.com with SMTP; 26 Oct 2021 02:13:47 -0700 Received: by stinkbox (sSMTP sendmail emulation); Tue, 26 Oct 2021 12:13:46 +0300 Date: Tue, 26 Oct 2021 12:13:46 +0300 From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= To: Jani Nikula Cc: intel-gfx@lists.freedesktop.org, Manasi Navare Message-ID: References: <20211026084208.2574-1-jani.nikula@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20211026084208.2574-1-jani.nikula@intel.com> X-Patchwork-Hint: comment Subject: Re: [Intel-gfx] [PATCH] drm/i915/dp: fix integer overflow in 128b/132b data rate calculation 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: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On Tue, Oct 26, 2021 at 11:42:07AM +0300, Jani Nikula wrote: > The intermediate value 1000000 * 10 * 9671 overflows 32 bits, so force > promotion to a bigger type. > > >From the logs: > > [drm:intel_dp_compute_config [i915]] DP link rate required 3657063 available -580783288 > > Fixes: 48efd014f0ea ("drm/i915/dp: add max data rate calculation for UHBR rates") > Cc: Manasi Navare > Cc: Ville Syrjälä > Signed-off-by: Jani Nikula > --- > drivers/gpu/drm/i915/display/intel_dp.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c > index f5dc2126d140..9a0cd2e1ebea 100644 > --- a/drivers/gpu/drm/i915/display/intel_dp.c > +++ b/drivers/gpu/drm/i915/display/intel_dp.c > @@ -352,7 +352,7 @@ intel_dp_max_data_rate(int max_link_rate, int max_lanes) > */ > int max_link_rate_kbps = max_link_rate * 10; > > - max_link_rate_kbps = DIV_ROUND_CLOSEST_ULL(max_link_rate_kbps * 9671, 10000); > + max_link_rate_kbps = DIV_ROUND_CLOSEST_ULL(max_link_rate_kbps * 9671UL, 10000UL); UL is not 64bit on 32bit architectures. Also having a 64bit divisor would be wasteful. DIV_ROUND_CLOSEST_ULL(mul_u32_u32(...), 10000); > max_link_rate = max_link_rate_kbps / 8; > } > > -- > 2.30.2 -- Ville Syrjälä Intel