On Fri, Jun 01, 2018 at 04:26:43PM -0500, Pierre-Louis Bossart wrote:
For codec master mode, the current pcm512x code relies on the clock API.
Simple boards such as Hifiberry DAC+ PRO rely on 2 local oscillators to generate 44.1 or 48kHz multiples, with the clock selection being handled by the machine driver toggling GPIOS.
The RaspberryPi kernel exposes a "hifiberry,dacpro-clk" clock driver which does nothing but tell the codec driver what rate is set by the machine driver [1][2]
This patch suggests an alternate fallback solution to let the codec driver know what the sysclk is based on the existing .set_sysclk callback.
I'm not seeing a great advantage in this - we want to have more adoption of standard APIs for clocking rather than less. As that Pi board shows it's easy to create static clocks in the clock API so why not just do that?