On Fri, Mar 15, 2024 at 06:36:19PM +0100, Alexandre Mergnat wrote: > On 15/03/2024 16:15, Mark Brown wrote: > > On Fri, Mar 15, 2024 at 04:05:21PM +0100, Alexandre Mergnat wrote: > > > > In the register. You only need to reset the gain to -40dB at the start > > > > of the ramp. > > > Sorry but I don't understand your logic, I'm not able to implement it... > > > If I'm at -10dB and doing a ramp to reach -40dB, next time I will read the > > > register the value will be -40dB. > > After we've done the ramp and turned the amplifier off we can just > > restore the desired value? The hardware is not going to care what the > > volume is while it's not enabled. > If you do that, HP will be enabled at the saved gain, and after that you > will do the ramp. To avoid pop, the driver should be rewrite to: So reset the volume to -40dB prior to turning the amplifier on... > Read gain in the reg and save it locally > Set -40dB in the reg > Enable HP > Do ramp ...as you yourself suggest? > > > AFAII from the comment in the code, it's done to avoid the "pop noises". > > Yes, that's the usual reason to ramp gains. Though if you've just > > copied the code without checking that it's needed it's possible that > > this is something that's been fixed in current hardware. > I did the test at 24dB with and without the "pop filter". Isn't big but I > ear the pop at the start of the record without the "pop filter". OK, it probably is still doing something then. > To be clear, the algo/behavior of this code is an implementation based on > the 6k+ lines downstream code for this specific audio codec. But the > shape/style is based on upstreamed drivers like mt6358.c. The Mediatek code has a bunch of issues, I wouldn't read too much into something being present in the code.
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