[alsa-devel] [PATCH 1/4] ASOC: tegra: move AC97 clock defines to the controller node

Mark Brown broonie at kernel.org
Wed Jul 24 11:44:01 CEST 2013

On Mon, Jul 22, 2013 at 06:26:20PM +0200, Lucas Stach wrote:
> Am Montag, den 22.07.2013, 10:46 +0100 schrieb Mark Brown:
> > On Mon, Jul 22, 2013 at 09:08:47AM +0200, Lucas Stach wrote:

> > > The clocks used by the Tegra ASoC utils were defined in the machine
> > > driver DT node for all boards, as this is were they get requested by the
> > > I2C and SPDIF Tegra audio drivers. Differently from those two the AC97

> > Why is the way the other devices are doing this sensible?

> Because they only need those clocks when actually playing audio, so
> requesting them late in the process when loading the machine driver is
> perfectly fine for them. The AC97 controller however already needs those
> clocks when initializing the controller and codec, so it has to request
> them earlier.

But why does it make sense to do that?  The clocks are directly
connected to the IP blocks in hardware after all..
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