ASoC: rt9120: Use pm_runtime and regcache to optimize 'pwdnn' logic
From the datasheet, the only way to meet the lowest power consumption is
to pull low the 'pwdnn' gpio. But if it is low, IC will keep in
reset state, all registers reset to default.
And the power consumption is listed below
1. amp off and 'pwdnn' high => idle state, PVDD = 1mA, DVDD = 7mA
2. amp off and 'pwdnn' low => shutdown state, PVDD < 20uA, DVDD < 15uA
It's the large difference for the consumption current
This fix is to use pm_runtime and regcache to handle 'pwdnn' gpio
control.
Signed-off-by: ChiYuan Huang <cy_huang@richtek.com>
Link: https://lore.kernel.org/r/1652926418-8519-3-git-send-email-u0084500@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>