From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1162608Ab3LFN2w (ORCPT ); Fri, 6 Dec 2013 08:28:52 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:44434 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161802Ab3LFNDl (ORCPT ); Fri, 6 Dec 2013 08:03:41 -0500 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Alex Deucher , Luis Henriques Subject: [PATCH 3.11 186/272] drm/radeon: use 64-bit math to calculate CTS values for audio (v2) Date: Fri, 6 Dec 2013 12:57:55 +0000 Message-Id: <1386334761-25517-187-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.8.3.2 In-Reply-To: <1386334761-25517-1-git-send-email-luis.henriques@canonical.com> References: <1386334761-25517-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.11 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.11.10.1 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Alex Deucher commit 062c2e4363451d49ef840232fe65e8bff0dde2a5 upstream. Avoid losing precision. See bug: https://bugs.freedesktop.org/show_bug.cgi?id=69675 v2: fix math as per Anssi's comments. Signed-off-by: Alex Deucher Signed-off-by: Luis Henriques --- drivers/gpu/drm/radeon/r600_hdmi.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/radeon/r600_hdmi.c b/drivers/gpu/drm/radeon/r600_hdmi.c index a74c2aa..14e19aa 100644 --- a/drivers/gpu/drm/radeon/r600_hdmi.c +++ b/drivers/gpu/drm/radeon/r600_hdmi.c @@ -75,8 +75,15 @@ static const struct radeon_hdmi_acr r600_hdmi_predefined_acr[] = { */ static void r600_hdmi_calc_cts(uint32_t clock, int *CTS, int N, int freq) { - if (*CTS == 0) - *CTS = clock * N / (128 * freq) * 1000; + u64 n; + u32 d; + + if (*CTS == 0) { + n = (u64)clock * (u64)N * 1000ULL; + d = 128 * freq; + do_div(n, d); + *CTS = n; + } DRM_DEBUG("Using ACR timing N=%d CTS=%d for frequency %d\n", N, *CTS, freq); } -- 1.8.3.2