From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Airlie Subject: [PATCH] drm/mgag200: fix G200ER pll picking algorithm Date: Thu, 9 Aug 2012 15:04:25 +1000 Message-ID: <1344488665-26792-1-git-send-email-airlied@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by gabe.freedesktop.org (Postfix) with ESMTP id 4ABC89E776 for ; Wed, 8 Aug 2012 22:04:28 -0700 (PDT) Received: from int-mx12.intmail.prod.int.phx2.redhat.com (int-mx12.intmail.prod.int.phx2.redhat.com [10.5.11.25]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id q7954RmC021237 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Thu, 9 Aug 2012 01:04:27 -0400 Received: from prime.bne.redhat.com (dhcp-41-76.bne.redhat.com [10.64.41.76]) by int-mx12.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id q7954Ps6004410 for ; Thu, 9 Aug 2012 01:04:26 -0400 List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dri-devel-bounces+sf-dri-devel=m.gmane.org@lists.freedesktop.org Errors-To: dri-devel-bounces+sf-dri-devel=m.gmane.org@lists.freedesktop.org To: dri-devel@lists.freedesktop.org List-Id: dri-devel@lists.freedesktop.org The original code was misported from the X driver, a) an int went to unsigned int, breaking the downward counting testm code b) the port did the vco/computed clock bits completely wrong. This fixes an infinite loop on modprobe on some Dell servers with the G200ER chipset variant. Found in internal testing. Cc: stable@vger.kernel.org Signed-off-by: Dave Airlie --- drivers/gpu/drm/mgag200/mgag200_mode.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c index d303061..0201d1d 100644 --- a/drivers/gpu/drm/mgag200/mgag200_mode.c +++ b/drivers/gpu/drm/mgag200/mgag200_mode.c @@ -468,10 +468,11 @@ static int mga_g200er_set_plls(struct mga_device *mdev, long clock) { unsigned int vcomax, vcomin, pllreffreq; unsigned int delta, tmpdelta; - unsigned int testr, testn, testm, testo; + int testr, testn, testm, testo; unsigned int p, m, n; - unsigned int computed; + unsigned int computed, vco; int tmp; + const unsigned int m_div_val[] = { 1, 2, 4, 8 }; m = n = p = 0; vcomax = 1488000; @@ -490,12 +491,13 @@ static int mga_g200er_set_plls(struct mga_device *mdev, long clock) if (delta == 0) break; for (testo = 5; testo < 33; testo++) { - computed = pllreffreq * (testn + 1) / + vco = pllreffreq * (testn + 1) / (testr + 1); - if (computed < vcomin) + if (vco < vcomin) continue; - if (computed > vcomax) + if (vco > vcomax) continue; + computed = vco / (m_div_val[testm] * (testo + 1)); if (computed > clock) tmpdelta = computed - clock; else -- 1.7.10.4