On Sun, 06 Jun 2021 16:16:44 +0200, Geoffrey D. Bennett wrote:
These two patches add support for reading the mixer volumes and mux configuration from the hardware when the driver is initialising.
Previously the ALSA volume controls were initialised to zero and the mux configuration set to a fixed default instead of being initialised to match the hardware state.
The ALSA controls for the Scarlett Gen 2 interfaces should now always be in sync with the hardware. Thanks to Vladimir Sadovnikov for figuring out how to do this.
Takashi, if these pass your review, I believe that they are appropriate for: #Cc: stable@vger.kernel.org
Well, in general, having a proper fixed value for the initial mixer value is the right thing, which is a part of the driver's role. Though, in snd-usb-audio, we don't set up the initial values just because of laziness; since the topology in USB audio is variable per device and often hard to parse correctly, it's difficult to determine the suitable initial values, hence we leave untouched. So, in that sense, setting the zero isn't wrong, rather safer, per se.
However, Scarlett 2 seems to want to be different; it has already some initialization code to read the existing configs. So this change sounds more or less acceptable. But it's questionable whether it's really for stable as a "fix".
In anyway, please fix the bug ktest bot spotted, the missing endian conversions and resubmit.
thanks,
Takashi