linux-kernel - Re: [PATCH] ASoC: wm8804: Allow control of master clock divider in PLL generation

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Message-ID: <20140113111431.GA26419@opensource.wolfsonmicro.com>
Date:	Mon, 13 Jan 2014 11:14:31 +0000
From:	Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>
To:	Daniel Matuschek <daniel@...uschek.net>
Cc:	alsa-devel@...a-project.org, Dimitris.Papastamos@...fsonmicro.com,
	tiwai@...e.de, linux-kernel@...r.kernel.org,
	patches@...nsource.wolfsonmicro.com, lgirdwood@...il.com,
	perex@...ex.cz, broonie@...nel.org, info@...zy-audio.com
Subject: Re: [PATCH] ASoC: wm8804: Allow control of master clock divider in
	PLL generation

On Sun, Jan 12, 2014 at 10:11:25PM +0100, Daniel Matuschek wrote:
> Signed-off-by: Daniel Matuschek <daniel@...uschek.net>
> 
> After some discussions of the patch last week, here is a new version. 
> Simply reducing the post_table did not work, as for some frequencies
> both settings (MCLKDIV=0 and MCLKDIV=1) are needed (e.g. 96 and 192kHz)
> 
> 
>   WM8804 can run with PLL frequencies of 256xfs and 128xfs for
>   most sample rates. At 192kHz only 128xfs is supported. The
>   existing driver selects 128xfs automatically for some lower
>   samples rates. By using an additional mclk_div divider, is
>   is now possible to control the behaviour. This allows using
>   256xfs PLL frequency on all sample rates up to 96kHz. It
>   should allow lower jitter and better signal quality. The
>   behavior has to be controlled by the sound card driver,
>   because some sample frequency share the same setting. e.g.
>   192kHz and 96kHz use 24.576MHz master clock. The only
>   difference is the MCLK divider.
> 

Commit message still needs fixed up, as per Mark's comments on
your last patch. Otherwise looks ok to me.

Thanks,
Charles
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