From patchwork Tue Sep 24 18:26:20 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?b?VmlsbGUgU3lyasOkbMOk?= X-Patchwork-Id: 2935161 Return-Path: X-Original-To: patchwork-intel-gfx@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 6D3959F524 for ; Tue, 24 Sep 2013 18:28:55 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 630612044C for ; Tue, 24 Sep 2013 18:28:54 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) by mail.kernel.org (Postfix) with ESMTP id 6C16620434 for ; Tue, 24 Sep 2013 18:28:53 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 67D05E78B0 for ; Tue, 24 Sep 2013 11:28:53 -0700 (PDT) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by gabe.freedesktop.org (Postfix) with ESMTP id 05CC1E73A9 for ; Tue, 24 Sep 2013 11:27:05 -0700 (PDT) Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga101.fm.intel.com with ESMTP; 24 Sep 2013 11:27:04 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.90,972,1371106800"; d="scan'208";a="406550659" Received: from stinkbox.fi.intel.com (HELO stinkbox) ([10.237.72.167]) by fmsmga002.fm.intel.com with SMTP; 24 Sep 2013 11:27:02 -0700 Received: by stinkbox (sSMTP sendmail emulation); Tue, 24 Sep 2013 21:27:02 +0300 From: ville.syrjala@linux.intel.com To: intel-gfx@lists.freedesktop.org Date: Tue, 24 Sep 2013 21:26:20 +0300 Message-Id: <1380047191-3359-4-git-send-email-ville.syrjala@linux.intel.com> X-Mailer: git-send-email 1.8.1.5 In-Reply-To: <1380047191-3359-1-git-send-email-ville.syrjala@linux.intel.com> References: <1380047191-3359-1-git-send-email-ville.syrjala@linux.intel.com> MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH 03/14] drm/i915: Make vlv_find_best_dpll() ppm calculation safe X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.13 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces+patchwork-intel-gfx=patchwork.kernel.org@lists.freedesktop.org Errors-To: intel-gfx-bounces+patchwork-intel-gfx=patchwork.kernel.org@lists.freedesktop.org X-Spam-Status: No, score=-6.5 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Ville Syrjälä Use div_u64() to make the ppm calculation in vlv_find_best_dpll() safe against interger overflows. Signed-off-by: Ville Syrjälä --- drivers/gpu/drm/i915/intel_display.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index 4b1af94..f8d67b2 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -673,13 +673,11 @@ vlv_find_best_dpll(const intel_limit_t *limit, struct drm_crtc *crtc, u32 p1, p2, m1, m2, vco, bestn, bestm1, bestm2, bestp1, bestp2; u32 m, n, fastclk; u32 updrate, minupdate, p; - unsigned long bestppm, ppm, absppm; + unsigned int bestppm = 1000000; int dotclk, flag; flag = 0; dotclk = target * 1000; - bestppm = 1000000; - ppm = absppm = 0; fastclk = dotclk / (2*100); updrate = 0; minupdate = 19200; @@ -696,6 +694,8 @@ vlv_find_best_dpll(const intel_limit_t *limit, struct drm_crtc *crtc, p = p1 * p2; /* based on hardware requirement, prefer bigger m1,m2 values */ for (m1 = limit->m1.min; m1 <= limit->m1.max; m1++) { + unsigned int ppm, diff; + m2 = DIV_ROUND_CLOSEST(fastclk * p * n, refclk * m1); m = m1 * m2; vco = updrate * m; @@ -703,14 +703,14 @@ vlv_find_best_dpll(const intel_limit_t *limit, struct drm_crtc *crtc, if (vco < limit->vco.min || vco >= limit->vco.max) continue; - ppm = 1000000 * ((vco / p) - fastclk) / fastclk; - absppm = (ppm > 0) ? ppm : (-ppm); - if (absppm < 100 && ((p1 * p2) > (bestp1 * bestp2))) { + diff = abs(vco / p - fastclk); + ppm = div_u64(1000000ULL * diff, fastclk); + if (ppm < 100 && ((p1 * p2) > (bestp1 * bestp2))) { bestppm = 0; flag = 1; } - if (absppm < bestppm - 10) { - bestppm = absppm; + if (ppm < bestppm - 10) { + bestppm = ppm; flag = 1; } if (flag) {