On Tue, May 09, 2023 at 09:38:46PM +0200, Martin Povišer wrote:
On 9. 5. 2023, at 20:25, Conor Dooley conor@kernel.org wrote:
00: 8.4 V Full-Scale Gain Mapping01: 12.6 V Full-Scale Gain Mapping10: 14 V Full-Scale Gain Mapping11: 15 V Full-Scale Gain Mapping
Putting register values into the DT does not seem correct, although I know nothing about sound and will have to defer to Krzysztof & Co. on that front.
I thought this should be here, and not with the other gain controls to be exported to userspace, since it relates to the supply voltage. You probably can’t select a gain value close or over the amp’s supply and expect proper functioning, so the value here should be the system’s integrator choice.
On second thought there doesn’t seem to be any risk of damage to the amp itself, so the knowledge of what’s the optimal value could be left up to ALSA use-case configuration, and there’s no real downside in treating it like other gain controls.
Alternatively why not just query the supply voltage via the regulator API? Those are kind of weird numbers (eg, 12.6V rather than 12V) though, it looks like they're not expected to be the actual maximum supply values but rather something slightly less.