[alsa-devel] [PATCH] ASoC: sgtl5000: Do not read registers prior to turning on the supplies

Marek Vasut marex at denx.de
Fri May 31 17:45:50 CEST 2013

Hi Fabio,

> On Fri, May 31, 2013 at 12:32 PM, Marek Vasut <marex at denx.de> wrote:
> > There was no problem without these patches though. With your patches, I
> > see NAK happening on the I2C lines upon first 2-byte write.
> Yes, but prior to these patches there were no register writes in sgtl5000.

How would volume adjustment work with no writes ? ;-)

> These addditional writes does work and solve the reset issues on
> mx6qsabrelite/mx51evk.
> It is only on mx28evk that we have this timeout issue.
> I think we need to turn on the SAIF clock (that connects to the
> sgtl5000 MCLK) prior to doing the I2C writes.

Ah, that's _very_ likely. I think the chip will NAK I2C communication without 
having clock supplied to it. I did look into this stuff with an LA yesterday 
night and I saw the 2-byte write followed by I2C NAK.

Best regards,
Marek Vasut

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