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

Lucas Stach dev at lynxeye.de
Mon Jul 22 18:26:20 CEST 2013

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:
> > Am Montag, den 22.07.2013, 00:36 +0100 schrieb Mark Brown:
> > > I'm sorry but I just don't understand what this change is supposed to do
> > > - what is the current place, what is wrong with it and what is the
> > > correct place?
> > 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
> > driver has to request those clocks in the controller drivers, as they
> > are needed at this point for proper initialisation.
> > So the patch moves the clocks from the machine driver node to the AC97
> > controller DT node, so they can be requested in the right driver.
> 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.


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