From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1751170AbbIEIbo (ORCPT <rfc822;w@1wt.eu>);
	Sat, 5 Sep 2015 04:31:44 -0400
Received: from pandora.arm.linux.org.uk ([78.32.30.218]:51922 "EHLO
	pandora.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1750893AbbIEIb1 (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Sat, 5 Sep 2015 04:31:27 -0400
Date: Sat, 5 Sep 2015 09:31:08 +0100
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Doug Anderson <dianders@chromium.org>
Cc: "open list:ARM/Rockchip SoC..." <linux-rockchip@lists.infradead.org>,
        alsa-devel@alsa-project.org,
        "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        Andy Yan <andy.yan@rock-chips.com>, Yakir Yang <ykk@rock-chips.com>,
        Fabio Estevam <fabio.estevam@freescale.com>,
        Mark Brown <broonie@kernel.org>, Takashi Iwai <tiwai@suse.de>,
        Jaroslav Kysela <perex@perex.cz>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Jon Nettleton <jon.nettleton@gmail.com>,
        David Airlie <airlied@linux.ie>
Subject: Re: [PATCH 6/9] drm: bridge/dw_hdmi: adjust pixel clock values in N
 calculation
Message-ID: <20150905083107.GK21084@n2100.arm.linux.org.uk>
References: <20150808160936.GN7557@n2100.arm.linux.org.uk>
 <E1ZO6hc-0003NW-55@rmk-PC.arm.linux.org.uk>
 <CAD=FV=WXjcp-wyH_SKexHJDo8R9Xug4yMAOHFPWPYBgiTyM=PQ@mail.gmail.com>
 <CAD=FV=WnVLiCNYgZ8idpknD==Rw7UaLCY1gky4G0TvwUR-VATw@mail.gmail.com>
 <20150904212401.GI21084@n2100.arm.linux.org.uk>
 <CAD=FV=U7h6b1eR+cva6VywcLP8RL2p5sAMSWc_vzUCg6WfWCYQ@mail.gmail.com>
 <20150905002733.GJ21084@n2100.arm.linux.org.uk>
 <CAD=FV=WR4iJ57FLh1d46-s9Gu-4wW6NdoROx-kNbbA0zFpUo0w@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CAD=FV=WR4iJ57FLh1d46-s9Gu-4wW6NdoROx-kNbbA0zFpUo0w@mail.gmail.com>
User-Agent: Mutt/1.5.23 (2014-03-12)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Fri, Sep 04, 2015 at 07:03:11PM -0700, Doug Anderson wrote:
> AKA: just replace your entire "compute_n" function with:
> 
> return (128 * freq) / 1000;
> 
> ...and it's 100% simpler _and_ gets you a (marginally) better rate
> (assuming you really have 22.175000).  If it was just about a
> 32000.222 vs 32000 I'd not be saying anything right now.  It's about
> adding complexity.

No.  It doesn't work for all cases.  Do the calculations for every
sample rate in those tables in the HDMI spec, and you'll find out
why.

-- 
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.