linux-kernel - Re: [PATCH 6/9] drm: bridge/dw_hdmi: adjust pixel clock values in N calculation

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20150905083107.GK21084@n2100.arm.linux.org.uk>
Date:	Sat, 5 Sep 2015 09:31:08 +0100
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Doug Anderson <dianders@...omium.org>
Cc:	"open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
	alsa-devel@...a-project.org,
	"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	Andy Yan <andy.yan@...k-chips.com>,
	Yakir Yang <ykk@...k-chips.com>,
	Fabio Estevam <fabio.estevam@...escale.com>,
	Mark Brown <broonie@...nel.org>, Takashi Iwai <tiwai@...e.de>,
	Jaroslav Kysela <perex@...ex.cz>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Jon Nettleton <jon.nettleton@...il.com>,
	David Airlie <airlied@...ux.ie>
Subject: Re: [PATCH 6/9] drm: bridge/dw_hdmi: adjust pixel clock values in N
 calculation

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.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/