From patchwork Mon Mar 7 22:48:10 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kamal Mostafa X-Patchwork-Id: 593546 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id 22104140322; Tue, 8 Mar 2016 09:54:57 +1100 (AEDT) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1ad43C-0000a2-Vs; Mon, 07 Mar 2016 22:54:54 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.76) (envelope-from ) id 1ad41a-0007zB-2G for kernel-team@lists.ubuntu.com; Mon, 07 Mar 2016 22:53:14 +0000 Received: from 1.general.kamal.us.vpn ([10.172.68.52] helo=fourier) by youngberry.canonical.com with esmtpsa (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.76) (envelope-from ) id 1ad41Z-0000FH-I8; Mon, 07 Mar 2016 22:53:13 +0000 Received: from kamal by fourier with local (Exim 4.86) (envelope-from ) id 1ad41W-0001xY-T4; Mon, 07 Mar 2016 14:53:10 -0800 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Subject: [PATCH 4.2.y-ckt 099/273] drm: Add drm_fixp_from_fraction and drm_fixp2int_ceil Date: Mon, 7 Mar 2016 14:48:10 -0800 Message-Id: <1457391064-6660-100-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 2.7.0 In-Reply-To: <1457391064-6660-1-git-send-email-kamal@canonical.com> References: <1457391064-6660-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 4.2 Cc: Dave Airlie , Kamal Mostafa , Harry Wentland X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com 4.2.8-ckt5 -stable review patch. If anyone has any objections, please let me know. ---8<------------------------------------------------------------ From: Harry Wentland commit 64566b5e767f9bc3161055ca1b443a51afb52aad upstream. drm_fixp_from_fraction allows us to create a fixed point directly from a fraction, rather than creating fixed point values and dividing later. This avoids overflow of our 64 bit value for large numbers. drm_fixp2int_ceil allows us to return the ceiling of our fixed point value. [airlied: squash Jordan's fix] 32-bit-build-fix: Jordan Lazare Signed-off-by: Harry Wentland Reviewed-by: Alex Deucher Signed-off-by: Dave Airlie Signed-off-by: Kamal Mostafa --- include/drm/drm_fixed.h | 53 +++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 51 insertions(+), 2 deletions(-) diff --git a/include/drm/drm_fixed.h b/include/drm/drm_fixed.h index d639049..553210c 100644 --- a/include/drm/drm_fixed.h +++ b/include/drm/drm_fixed.h @@ -73,18 +73,28 @@ static inline u32 dfixed_div(fixed20_12 A, fixed20_12 B) #define DRM_FIXED_ONE (1ULL << DRM_FIXED_POINT) #define DRM_FIXED_DECIMAL_MASK (DRM_FIXED_ONE - 1) #define DRM_FIXED_DIGITS_MASK (~DRM_FIXED_DECIMAL_MASK) +#define DRM_FIXED_EPSILON 1LL +#define DRM_FIXED_ALMOST_ONE (DRM_FIXED_ONE - DRM_FIXED_EPSILON) static inline s64 drm_int2fixp(int a) { return ((s64)a) << DRM_FIXED_POINT; } -static inline int drm_fixp2int(int64_t a) +static inline int drm_fixp2int(s64 a) { return ((s64)a) >> DRM_FIXED_POINT; } -static inline unsigned drm_fixp_msbset(int64_t a) +static inline int drm_fixp2int_ceil(s64 a) +{ + if (a > 0) + return drm_fixp2int(a + DRM_FIXED_ALMOST_ONE); + else + return drm_fixp2int(a - DRM_FIXED_ALMOST_ONE); +} + +static inline unsigned drm_fixp_msbset(s64 a) { unsigned shift, sign = (a >> 63) & 1; @@ -136,6 +146,45 @@ static inline s64 drm_fixp_div(s64 a, s64 b) return result; } +static inline s64 drm_fixp_from_fraction(s64 a, s64 b) +{ + s64 res; + bool a_neg = a < 0; + bool b_neg = b < 0; + u64 a_abs = a_neg ? -a : a; + u64 b_abs = b_neg ? -b : b; + u64 rem; + + /* determine integer part */ + u64 res_abs = div64_u64_rem(a_abs, b_abs, &rem); + + /* determine fractional part */ + { + u32 i = DRM_FIXED_POINT; + + do { + rem <<= 1; + res_abs <<= 1; + if (rem >= b_abs) { + res_abs |= 1; + rem -= b_abs; + } + } while (--i != 0); + } + + /* round up LSB */ + { + u64 summand = (rem << 1) >= b_abs; + + res_abs += summand; + } + + res = (s64) res_abs; + if (a_neg ^ b_neg) + res = -res; + return res; +} + static inline s64 drm_fixp_exp(s64 x) { s64 tolerance = div64_s64(DRM_FIXED_ONE, 1000000);