linux-kernel - Re: [PATCH v1 1/5] ASoC: rockchip: i2s: Support to set the divider clock API

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Message-ID: <20151105161615.GS18409@sirena.org.uk>
Date:	Thu, 5 Nov 2015 16:16:15 +0000
From:	Mark Brown <broonie@...nel.org>
To:	Caesar Wang <caesar.upstream@...il.com>
Cc:	Caesar Wang <wxt@...k-chips.com>, alsa-devel@...a-project.org,
	Heiko Stuebner <heiko@...ech.de>,
	Liam Girdwood <lgirdwood@...il.com>,
	linux-kernel@...r.kernel.org, Takashi Iwai <tiwai@...e.com>,
	Doug Anderson <dianders@...omium.org>,
	Jaroslav Kysela <perex@...ex.cz>,
	linux-rockchip@...ts.infradead.org,
	Dylan Reid <dgreid@...omium.org>,
	Sonny Rao <sonnyrao@...omium.org>,
	linux-arm-kernel@...ts.infradead.org,
	Cheng-Yi Chiang <cychiang@...omium.org>
Subject: Re: [PATCH v1 1/5] ASoC: rockchip: i2s: Support to set the divider
 clock API

On Thu, Nov 05, 2015 at 01:56:39PM +0800, Caesar Wang wrote:
> 在 2015年11月04日 22:34, Mark Brown 写道:

> >Same thing as your other very similar patch: why does this feature
> >require set_clkdiv()?

> Okay, you said "
> Why is this a requirement?  The clock to use as a source should normally
> be specified via set_sysclk() and any internal dividers calculated
> automatically by the driver.
> "

> I think we should divider settings for these different sample rates.

Sure, the question is how these things get set.

>  If the codec is master mode, we are *not* need this operate.
>  If the codec is slave mode, we are need to divider the MCLK to setting the different sample rates.
> (for example, the sample rates (8k, 48k) the clock is MCLK, the clock should be divider cpu ip )

> "dividers calculated automatically by the driver", that should be occured by codec(max98090
> ) driver, but the divider clocks (LRCK, SCLK) should need to set for cpu internal side.

So the CPU knows what rates it needs to set and what clocks it's getting
in, why can't it set the dividers autonomously.

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