[alsa-devel] question on dapm_reg_event()
jhnikula at gmail.com
Wed Jan 6 16:48:59 CET 2010
On Wed, 6 Jan 2010 14:53:22 +0000
Mark Brown <broonie at opensource.wolfsonmicro.com> wrote:
> On Mon, Jan 04, 2010 at 09:10:27PM -0500, Haojian Zhuang wrote:
> > I just have a question on dapm code. In dapm_reg_event(), -(w->reg +
> > 1) is input parameter of snd_soc_update_bits(). Why we need to use
> > negative value as input parameter at here? Why do we not use w->reg at
> > here?
> Hrm, no, that's not at all clear to me either. CCing Jarkko who
> contributed the register write control originally.
IIRC, there were some reason to avoid register update by the
dapm_update_bits and negative register value was used to prevent it.
Reg+1 makes sure that the value is negative also for register 0.
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