On Thu, May 17, 2018 at 8:30 AM, Marco Felsch <m.felsch@xxxxxxxxxxxxxx> wrote: > From: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx> > > According to the ssm2603 data sheet (control register sequencing), the > digital core should be activated only after all necessary bits in the > power register are enabled, and a delay determined by the decoupling > capacitor on the VMID pin has passed. If the digital core is activated > too early, or even before the ADC is powered up, audible artifacts > appear at the beginning of the recorded signal. > > The digital core is also needed for playback, so when recording starts > it may already be enabled. This means we cannot get the power sequence > correct when we want to be able to start recording after playback. > > As a workaround put the MIC mute switch into the DAPM routes. This > way we can keep the recording disabled until the MIC Bias has settled > and thus get rid of audible artifacts. > > The delay we have to wait depends on a board specific capacitor > connected to the VMID pins, so make the delay configurable in the device > tree. > > Signed-off-by: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx> > Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx> > Signed-off-by: Marco Felsch <m.felsch@xxxxxxxxxxxxxx> > --- > .../devicetree/bindings/sound/adi,ssm2602.txt | 7 +++++ > sound/soc/codecs/ssm2602.c | 30 +++++++++++++++++-- > 2 files changed, 35 insertions(+), 2 deletions(-) > > diff --git a/Documentation/devicetree/bindings/sound/adi,ssm2602.txt b/Documentation/devicetree/bindings/sound/adi,ssm2602.txt > index 3b3302fe399b..9334d48c0462 100644 > --- a/Documentation/devicetree/bindings/sound/adi,ssm2602.txt > +++ b/Documentation/devicetree/bindings/sound/adi,ssm2602.txt > @@ -11,9 +11,16 @@ Required properties: > - reg : the I2C address of the device for I2C, the chip select > number for SPI. > > +Optional properties: > + > + - startup-delay-us : delay between powering on and activating the digital > + core, determined by the decoupling capacitor C on the > + VMID pin: delay [µs] = C [µF] * 25000 / 3.5 > + We already have similarly defined property. Please reuse that. See mmc pwrseq binding. Also, please split bindings to separate patch. Rob -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
