linux-kernel - Re: [PATCH] ASoC: kirkwood-i2s: fix a compilation warning

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Date:	Mon, 15 Jul 2013 21:08:51 +0100
From:	Mark Brown <broonie@...nel.org>
To:	Jean-Francois Moine <moinejf@...e.fr>
Cc:	Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.de>,
	alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
	Liam Girdwood <lgirdwood@...il.com>,
	Russell King <rmk+kernel@....linux.org.uk>
Subject: Re: [PATCH] ASoC: kirkwood-i2s: fix a compilation warning

On Mon, Jul 15, 2013 at 08:37:56PM +0200, Jean-Francois Moine wrote:
> Mark Brown <broonie@...nel.org> wrote:

> > I'd really like to see an analysis explaining why this can never happen,
> > the driver explicitly supports running without extclk being provided.
> > Simply asserting that we should never get such a rate isn't really
> > enough detail...

> Russell explained this in the message below dated Wed, 27 Mar 2013
>   (http://www.spinics.net/lists/arm-kernel/msg233819.html)

This is no good, the information needs to be in the commit message.
Right now the change just looks like a bug supported by wishful
thinking, you're not providing enough analysis and inspection of the
code suggests a bug.

> Sebastian is correct in that such a path should _never_ be reached
> because ALSA will reject anything but 44.1, 48 or 96kHz rates if we
> don't have an extclk.

There's no obvious code that handles anything differently with extclk.
Indeed if you think about it for a minute you'll realise there's no way
the driver will ever use an extclk - set_rate() is badly implemented,
look at how other drivers select between clocks.

Fixing the driver so it can make use of an extclk would be more
useful...

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