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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 00364C3DA7A for ; Wed, 28 Dec 2022 15:29:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233766AbiL1P3m (ORCPT ); Wed, 28 Dec 2022 10:29:42 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47340 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233730AbiL1P3k (ORCPT ); Wed, 28 Dec 2022 10:29:40 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 289671572E for ; Wed, 28 Dec 2022 07:29:40 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id B052E6155C for ; Wed, 28 Dec 2022 15:29:39 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C6C7BC433F0; Wed, 28 Dec 2022 15:29:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1672241379; bh=OdE+smot/ZM5r/Fvd7ynQ+TbuW5OrN192l62Yjb/t7Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=y3tbWxxHFv0+2NHAXVyIFcadX/OLKmc98CK6BI6vp4L42So7mKil0umxhOh/GUvBq OBUN2gj3c6oxmhMUCeOtW6GY3XtLL3JisKTTaIK1C/VpqqZFIAiijIKLH0sUhWQ84t VLxxB95X264VJhWhRpwoxql/fDq2T5/L9b8TykDY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Abhinav Kumar , Dmitry Baryshkov , Marijn Suijten , Sasha Levin Subject: [PATCH 6.0 0273/1073] drm/msm/dsi: Remove useless math in DSC calculations Date: Wed, 28 Dec 2022 15:31:01 +0100 Message-Id: <20221228144335.432059275@linuxfoundation.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20221228144328.162723588@linuxfoundation.org> References: <20221228144328.162723588@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Marijn Suijten [ Upstream commit 01a907980e0be3310f18c7d4955968f3b28e7147 ] Multiplying a value by 2 and adding 1 to it always results in a value that is uneven, and that 1 gets truncated immediately when performing integer division by 2 again. There is no "rounding" possible here. After that target_bpp_x16 is used to store a multiplication of bits_per_pixel by 16 which is only ever read to immediately be divided by 16 again, and is elided in much the same way. Fixes: b9080324d6ca ("drm/msm/dsi: add support for dsc data") Reviewed-by: Abhinav Kumar Reviewed-by: Dmitry Baryshkov Signed-off-by: Marijn Suijten Patchwork: https://patchwork.freedesktop.org/patch/508932/ Link: https://lore.kernel.org/r/20221026182824.876933-2-marijn.suijten@somainline.org Signed-off-by: Dmitry Baryshkov Signed-off-by: Sasha Levin --- drivers/gpu/drm/msm/dsi/dsi_host.c | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-) diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c index 15e108be1901..843521c9cdcf 100644 --- a/drivers/gpu/drm/msm/dsi/dsi_host.c +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c @@ -1849,7 +1849,6 @@ static int dsi_populate_dsc_params(struct drm_dsc_config *dsc) int hrd_delay; int pre_num_extra_mux_bits, num_extra_mux_bits; int slice_bits; - int target_bpp_x16; int data; int final_value, final_scale; int i; @@ -1929,14 +1928,7 @@ static int dsi_populate_dsc_params(struct drm_dsc_config *dsc) data = 2048 * (dsc->rc_model_size - dsc->initial_offset + num_extra_mux_bits); dsc->slice_bpg_offset = DIV_ROUND_UP(data, groups_total); - /* bpp * 16 + 0.5 */ - data = dsc->bits_per_pixel * 16; - data *= 2; - data++; - data /= 2; - target_bpp_x16 = data; - - data = (dsc->initial_xmit_delay * target_bpp_x16) / 16; + data = dsc->initial_xmit_delay * dsc->bits_per_pixel; final_value = dsc->rc_model_size - data + num_extra_mux_bits; dsc->final_offset = final_value; -- 2.35.1