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 06342C433EF for ; Fri, 11 Feb 2022 11:14:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349370AbiBKLOB (ORCPT ); Fri, 11 Feb 2022 06:14:01 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:39386 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233659AbiBKLN7 (ORCPT ); Fri, 11 Feb 2022 06:13:59 -0500 Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4FC43E58; Fri, 11 Feb 2022 03:13:59 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1644578039; x=1676114039; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=dwLXbIIZzHbMAw4pY6RvQqqG4HJGRvuDXCe7ZYOPqv0=; b=KfqGZh09UBzL11pgwSKG30xWSfqG1k3JpAjUpUphyO3nLIdcibiiq4wB 9anS3lCqpGhFDPg4sfkWjZWmxXwfBfjrb+oPPC/wW0Pg05PCy9TwWaTyL CEUIp79nSNElv2MDMS920ZizQ81nc2vKPqmVj7Xu4CWM+0oQN3p2anCIL h+FqJfgHsjdOWW1hOQWO7br5V1Lw1WQ0d1hDnr7Y+y4QAJB4z045B+c8L 75h01SrxjI1XQgQWz0VozYmfY+YFxcSAk1CdU70gnPG5ISXevHiNUqGO+ LjAuG0WU50t+fiVxfaZ4eMMVjg2JJxi9r2Z7bsxkX16UxTNvWCVcqhD9Z Q==; X-IronPort-AV: E=McAfee;i="6200,9189,10254"; a="229679286" X-IronPort-AV: E=Sophos;i="5.88,360,1635231600"; d="scan'208";a="229679286" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Feb 2022 03:13:59 -0800 X-IronPort-AV: E=Sophos;i="5.88,360,1635231600"; d="scan'208";a="569011379" Received: from smile.fi.intel.com ([10.237.72.61]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Feb 2022 03:13:55 -0800 Received: from andy by smile.fi.intel.com with local (Exim 4.95) (envelope-from ) id 1nITrF-003Q2V-Nb; Fri, 11 Feb 2022 13:12:57 +0200 Date: Fri, 11 Feb 2022 13:12:57 +0200 From: Andy Shevchenko To: Javier Martinez Canillas Cc: linux-kernel@vger.kernel.org, linux-fbdev@vger.kernel.org, Geert Uytterhoeven , Maxime Ripard , Daniel Vetter , dri-devel@lists.freedesktop.org, Thomas Zimmermann , Sam Ravnborg , Noralf =?iso-8859-1?Q?Tr=F8nnes?= , Daniel Vetter , David Airlie , Maarten Lankhorst , Maxime Ripard Subject: Re: [PATCH v4 1/6] drm/format-helper: Add drm_fb_xrgb8888_to_gray8_line() Message-ID: References: <20220211091927.2988283-1-javierm@redhat.com> <20220211091927.2988283-2-javierm@redhat.com> <4fa465d9-4fac-4199-9a04-d8e09d164308@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4fa465d9-4fac-4199-9a04-d8e09d164308@redhat.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 11, 2022 at 11:40:13AM +0100, Javier Martinez Canillas wrote: > On 2/11/22 11:28, Andy Shevchenko wrote: > > On Fri, Feb 11, 2022 at 10:19:22AM +0100, Javier Martinez Canillas wrote: ... > >> +static void drm_fb_xrgb8888_to_gray8_line(u8 *dst, const u32 *src, unsigned int pixels) > >> +{ > >> + unsigned int x; > >> + > >> + for (x = 0; x < pixels; x++) { > >> + u8 r = (*src & 0x00ff0000) >> 16; > >> + u8 g = (*src & 0x0000ff00) >> 8; > >> + u8 b = *src & 0x000000ff; > >> + > >> + /* ITU BT.601: Y = 0.299 R + 0.587 G + 0.114 B */ > >> + *dst++ = (3 * r + 6 * g + b) / 10; > >> + src++; > >> + } > > > > Can be done as > > > > while (pixels--) { > > ... > > } > > > > or > > > > do { > > ... > > } while (--pixels); > > > > I don't see why a while loop would be an improvement here TBH. Less letters to parse when reading the code. > In any case, I just pulled the line conversion logic as a separate > function with minimal code changes since doing that should be in a > separate patch. > Feel free to post a patch if you want to change that while loop. Perhaps some day :-) -- With Best Regards, Andy Shevchenko